The influence of age on the recovery of the ERG photostress test.

INTRODUCTION: Focal ERG associated with photostress test could be a useful diagnostic method for evaluating macular visual function. The main aim of this study was to evaluate the effect of age on the recovery time constant of the ERG photostress test. The second aim was to assess the sources of variability which affect the measurements. METHODS: Fifty-four healthy subjects (108 eyes), aged between 21 and 77, with corrected VA of 20/20 or more and absence of any ocular or systemic disease, were recruited. For each eye ERG response to focal (20° in diameter) 42-Hz stimulation was recorded: three series of 200 summations in base conditions and a six series of 42-Hz ERGs (100 summations each) at 10, 40, 80, 180, 300 and 420 s after bleaching by a white spot of light (20° in diameter) from a direct ophthalmoscope (800 cd/m²) pointed at macular region for 30 s. Fourier analysis was performed and amplitude of the first harmonica calculated. The relationship of basal amplitudes with subject age and gender, and the kinetics of macular function recovery were assessed through mixed-effects models. RESULTS: Mean basal amplitude decreases by 0.046 µV for year of life. The recovery after bleaching is proportional to age with an increase of 4.31 s for decade. Restoration of amplitude is slower in older subjects. DISCUSSION: There is a significant decrease in macular ERG amplitude with age. The macular recovery after photostress shows exponential kinetics that are less efficient in older subjects: this could be related to lower effectiveness of photopigment restoration in advanced age.

Atrial natriuretic factor and arterial baroreceptor reflexes in unanesthetized rats.

The modulation exerted by atrial natriuretic factor (ANF) on the cardiac and vascular influences of arterial baroreceptors was investigated in two groups of unanesthetized, chronically instrumented normotensive rats. In group 1, the reflex control of heart rate was assessed by graded baroreceptor stimulations and deactivations obtained by intravenous boluses of phenylephrine and nitroprusside. Under either circumstance, baroreceptor reflex sensitivity was expressed as the linear regression slope relating the chronotropic responses to the drug-induced mean arterial pressure changes. In group 2, right common carotid occlusion was performed in rats with their aortic and left carotid sinus baroreceptors denervated to assess the baroreceptor control of blood pressure; the reflex response was quantitated as the peak blood pressure rise observed during the maneuver. The reflex studies were performed before and during atriopeptin III infusion (0.15-0.20 micrograms/kg/min for 60 minutes). ANF augmented the bradycardic response to phenylephrine by 102.5 +/- 29% (p less than 0.01), reduced the tachycardic response to nitroprusside by 67.7 +/- 6.4% (p less than 0.01), and failed to modify the pressor response to carotid occlusion (-6.8 +/- 2.1%, p = NS). In a separate group of rats infused with low dose nitroprusside, no change in the baroreceptor-heart rate reflex was observed. ANF infusion (0.20 micrograms/kg/min) performed in further separate groups of conscious rats raised plasma ANF to 480 +/- 58 fmol/ml. Values in control vehicle-infused rats were 50 +/- 8 fmol/ml. Vascular reactivity (pressor response to intravenous phenylephrine boluses in anesthetized, sinoaortic-denervated rats) was only minimally reduced by ANF.(ABSTRACT TRUNCATED AT 250 WORDS)

Spontaneous variability of regional haemodynamics in unanaesthetized rats.

AIM: To study the spontaneous variability in regional haemodynamics. METHODS: Twenty normotensive Wistar-Kyoto rats were chronically instrumented with an arterial catheter and with pulsed Doppler flowmeters on the distal aorta, and the superior mesenteric and left renal arteries. After surgical recovery, the rats were monitored in unrestrained conditions. The recorded signals were analysed beat-to-beat to obtain means and coefficients of variation for mean arterial pressure, heart rate, regional blood flow velocity (consecutive 0.8-s periods) and indices of regional vascular resistance (0.8-s ratio of mean arterial pressure to mean blood flow velocity). RESULTS: Muscle and splanchnic blood flow velocities were markedly variable, with coefficients of variation of 12.8 +/- 0.8 and 12.2 +/- 1.7% (means +/- SEM), respectively, about twice as large as the coefficient of variation for mean arterial pressure (6.2 +/- 0.3%). The renal blood flow velocity was slightly less variable than the muscle and splanchnic blood flow velocities, with a coefficient of variation of 10.4 +/- 0.8%, but still markedly and significantly more variable than systemic arterial pressure. A contingency analysis of paired variations in any two given parameters (arterial blood pressure, heart rate, blood flow velocities and indices of vascular resistance) showed a concordant pattern, the only exception being a distinctly discordant trend for the covariations in muscle and splanchnic blood flow velocities. CONCLUSIONS: Regional blood flow velocity and vascular resistance have a larger degree of spontaneous variability than systemic arterial pressure. Renal blood flow velocity is also highly variable, suggesting that short-term stimuli that affect the renal blood vessels are not countered by autoregulation to any great degree. We conclude that while central factors may drive concordant regional haemodynamic variations, some opposing changes in regional blood flow velocity may cancel each other out, thereby reducing the variability in systemic blood pressure.

A single-blind, placebo-controlled study of effects of atenolol on transient ischemia in "mixed" angina.

The efficacy of atenolol in preventing episodes of transient ischemia during daily life was evaluated in 10 patients with "mixed" angina who underwent a 4-week, single-blind, double-crossover placebo-controlled trial. On day 6 and 7 of each treatment phase, continuous ambulatory electrocardiographic monitoring was performed for 48 hours. On day 7 an exercise test was also performed. Two-hundred and sixty-four ischemic episodes (79% "silent") were recorded during placebo treatment; 98 were recorded during atenolol treatment (63% decrease, p less than 0.01). In agreement with previous observations, most ischemic episodes observed during placebo (156 or 59%) were not preceded by an increase in heart rate. Surprisingly, the beneficial effects of atenolol were more pronounced for these episodes than for those preceded by an increase in heart rate and apparently caused by an increase in myocardial demand (decreases of 72% and 48%, respectively). Painful and painless episodes were decreased by a similar extent. In all patients, the heart rate recorded at the beginning of ST-segment depression was widely variable and significantly lower with atenolol (64 +/- 14 beats/min) than with placebo (81 +/- 13 beats/min, p less than 0.05). During both placebo and atenolol treatment, the highest incidence of ischemic events was observed between 6 A.M. and 9 P.M., in coincidence with the highest levels of the heart rate resting.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquisition of hepatitis C virus in hemodialysis patients: a prospective study by branched DNA signal amplification assay.

Serological data indicate that hepatitis C virus (HCV) infection is very common among chronic hemodialysis (HD) patients. Circumstantial evidence suggests that hemodialysis per se is an important risk factor for this infection. We used a novel methodology, the branched DNA (bDNA) signal amplification assay, which is capable of detecting HCV RNA and of quantifying HCV viral load in serum, to prospectively determine the rate of acquisition of HCV infection in 274 anti-HCV-negative patients undergoing HD treatment in four hemodialysis units. Moreover, we used bDNA testing to analyze the dynamics of HCV acquisition among HD patients, a high-risk group for HCV infection with immune compromise conferred from uremia. Two patients were identified with de novo acquisition during 1 year of prospective bDNA testing. Thus, the HCV incidence was 0.73% per year. De novo acquisition of HCV infection was observed in the absence of identifiable parenteral risk factors. Both patients showed the same pattern of HCV acquisition: they underwent an initial viremic phase that was associated with an increase in alanine transaminase (ALT) activity and that preceded the anti-HCV seroconversion. This was followed by HCV RNA clearance and normalization of ALT activity. Anti-HCV positivity occurred 1 and 2 months after the ALT increase in the first and second patients, respectively. Although HCV incidence was low (0.73%), further research is warranted to set the optimal policy for eliminating the risk of nosocomial transmission of HCV in the HD setting. Our findings show the pattern of HCV acquisition in chronic HD patients and emphasize the need to screen the HD population for ALT measurement combined with anti-HCV testing for detecting hepatitis C. HCV RNA testing can identify HCV before seroconversion in individuals with deranged liver function tests. The acquisition of HCV in HD patients without identifiable risk is confirmed.

Impaired left ventricular filling dynamics in patients with angina and angiographically normal coronary arteries: effect of beta adrenergic blockade.

OBJECTIVE: To assess exercise performance and resting left ventricular filling dynamics in patients with syndrome X (SX) in basal conditions and after 10 days treatment with oral atenolol. DESIGN AND PATIENTS: Exercise performance was studied and left ventricular filling assessed by Doppler-derived transmitral flow pattern analysis in 22 patients (16 female, mean (SD) age 53 (4) years) with angina, a positive exercise test, and angiographically smooth coronary arteries. Patients were studied after two 10 day treatment periods with either atenolol or placebo in a single-blind, randomised, crossover trial. The same protocol was followed in 10 patients with documented coronary artery disease (CAD) and in 13 controls (C). RESULTS: Unlike the controls, patients with SX and those with CAD consistently showed exercise-induced ST segment abnormalities and impaired resting left ventricular filling while on placebo. Atenolol significantly reduced episodes of angina, completely prevented exercise-induced ST segment changes in 18 SX patients, and delayed their onset in all patients with CAD: in both groups the agent significantly improved Doppler-derived indices (mean (SD)) of ventricular filling (E/A 0.97 (0.27) v 1.22 (0.32) and 0.84 (0.21) v 1.19 (0.37), respectively). CONCLUSIONS: The objective documentation of left ventricular filling abnormalities may be useful in confirming the clinical diagnosis of SX and in providing objective evidence of therapeutic benefit. The similarity of the symptoms and electrocardiographic and ventricular filling abnormalities found in patients with SX and in those with CAD suggests that ischaemia is involved in both groups.

Protein S and protein C anticoagulant activity in acute and chronic cardiac ischemic syndromes. Relationship to inflammation, complement activation and in vivo thrombin activity.

Protein S (PS) and protein C (PC) anticoagulant activities and thrombin-antithrombin complex (TAT) were measured in 20 patients with AIS, 25 patients with chronic stable angina (CSA) and a control group (C). Although plasma levels of TAT were significantly elevated in patients with CSA (p < 0.01 vs C), they were much higher in patients with AIS (p < 0.001 vs CSA). PC anticoagulant activity was similar in patients and controls. At variance, PS anticoagulant activity was lower in patients with AIS than in those with CSA and controls (p < 0.05), reflecting differences in total PS and C4B-binding protein (C4B-BP) antigen possibly resulting from involvement in the mechanisms of inflammation, complement activation and acute-phase response. The ratios of anticoagulant PS and PC to procoagulant vitamin K-dependent factors IX and II were reduced in AIS patients (0.05 > p > 0.005 vs C). In addition, the ratios of anticoagulant PC and PS to factor IX were lower in patients with AIS than in those with CSA (p < 0.05). These results indicate that in patients with acute ischemic cardiac syndromes the markedly increased in vivo thrombin generation is associated with an unbalance between coagulant and anticoagulant vitamin K-dependent factors.

Age-related alterations in cardiac parasympathetic responsiveness: a preliminary report.

Baroreceptor control of the heart rate is reduced by ageing in animals and man. This has been ascribed to an age-related reduction in beta-adrenergic receptor density and cardiac responsiveness to sympathetic modulation. However, the baroreceptor-heart rate reflex largely depends on the vagus and the age-related changes in cardiac parasympathetic responsiveness have never been tested directly. We examined the heart rate responses to acetylcholine in six young (3-5 months) and six old (22-24 months) ketamine-anaesthetized, bilaterally vagotomized Sprague-Dawley rats instrumented with arterial and venous catheters. The acetylcholine was given as 2, 4 and 8 micrograms/kg intravenous bolus injections. Linear regressions between each dose of acetylcholine and the ensuing bradycardia were calculated. The acetylcholine-induced bradycardia was strikingly larger in old than in young rats, amounting to 20.9 +/- 4.4 and 8.6 +/- 1.5 beats/min per microgram per kg, respectively (P less than 0.05). Thus cardiac muscarinic receptor responsiveness is increased rather than reduced by ageing. Therefore not all functions involved in cardiovascular regulation show an age-related impairment, and some may even be enhanced as age progresses. It is also clear that mechanisms other than attenuation of cardiac responses to autonomic stimuli (central and/or afferent) account for the age-related impairment in the baroreceptor-heart rate reflex.

Effect of atrial natriuretic factor on arterial baroreceptor control of heart rate and blood pressure in conscious rats.

The effects of atrial natriuretic factor (ANF) on arterial baroreceptor control of heart rate and of blood pressure were examined in conscious normotensive rats chronically instrumented with arterial and venous catheters, by measuring (1) the pulse interval responses to four intravenous boluses of phenylephrine and four intravenous boluses of nitroprusside, reflex sensitivity being calculated as the slope of the linear relationship between pulse interval and mean arterial pressure (nine rats); (2) the pressor response to right common carotid occlusion (balloon-in-cuff occluder) in eight rats with aortic and left carotid baroreceptor denervation. The study was performed before and during a non-hypotensive infusion of ANF. Atrial natriuretic factor increased the bradycardic responses to phenylephrine by 90% but reduced the tachycardic response to nitroprusside by 67% (P less than 0.01 for both) and left the pressor response to carotid occlusion unaffected (-7%, NS). It is concluded that ANF modulates the arterial baroreceptor reflex in a complex fashion, with opposite responses to arterial baroreceptor stimulation and deactivation, and different responses for the cardiac and vascular component of the reflex.

Alterations in cardiac parasympathetic function in aged rats.

Aging impairs sympathetic and parasympathetic cardiac control. Although the reduced sympathetic responses are known to depend on an age-related cardiac beta-adrenoceptor dysfunction, the hypothesis of a parallel cardiac muscarinic receptor dysfunction underlying the reduced parasympathetic responses has never been tested. We therefore measured the bradycardic responses to graded electrical stimulations of the right efferent vagus and to graded bolus intravenous injections of acetylcholine in anesthetized, vagotomized rats of young (16 wk) and old (103 wk) age. Unexpectedly, the bradycardia was markedly larger (greater than 2-fold) in old than in young rats with both the electrical and the pharmacological stimulus. This indicates that at variance with its effects on beta-adrenergic receptor responsiveness, aging not only fails to impair but actually enhances cardiac muscarinic receptor responsiveness. It also suggests the more general conclusion that aging has complex and diversified effects rather than simply and uniformly depressing biological functions.

Beta-blockers for the treatment of angina pectoris: indications in relation to pathophysiological mechanisms.

In patients with ischaemic heart disease, therapeutic options should be selected on the basis of pathophysiological considerations. Classically, whereas calcium channel blockers and nitrates should be used in patients whose symptoms are more likely to result from coronary vasoconstriction, beta-blockers and revascularisation procedures should be considered when coronary flow reserve is severely limited by "fixed" atheroma. However, recent studies from our laboratory indicate that in patients with "mixed" angina whose symptoms are thought to be at least partially consequent to coronary vasoconstriction superimposed on atheromatous lesions of different severity, beta-blockers can also be effective in preventing episodes of myocardial ischaemia which occur during everyday life. Although most of these episodes are not apparently caused by an excessive increase in cardiac work, their number, severity, and duration are markedly reduced by beta-blocking agents. From these observations it is argued that, in patients with "mixed" angina, most ischaemic events are likely to be caused by transient reduction of regional myocardial perfusion, occurring for different levels of cardiac metabolic demand. The higher the latter, the more likely the former will be to precipitate clinical ischaemia.

Role of the sympathetic nervous system in the pathogenesis of chronic stable angina. Implications for the mechanism of action of beta-blockers.

Thirteen patients with chronic stable effort angina underwent continuous ambulatory electrocardiographic and intra-arterial blood pressure monitoring during normal unrestricted daily activity. Each patient underwent two studies, the first while on no treatment and the second while on beta-blocker therapy. During the control period, we recorded 182 episodes of transient ST-segment depression, of which only 30 were associated with angina, and 43 (24%) were apparently caused by increased myocardial oxygen demand. Although the majority of ischemic events (139) were not preceded by an increase in either heart rate or systolic arterial pressure, most occurred during the daytime when the levels of the rate-pressure product were higher. Throughout the day, beta-blockade significantly decreased the levels of heart rate and blood pressure and reduced the number of ischemic attacks by 56%, particularly if such attacks were not caused by increased myocardial demand. The diurnal distribution of ischemic events was not significantly affected by beta-blockade, and again, the majority were observed during the day, in coincidence with high resting levels of rate-pressure product. Whatever the behavior of heart rate and blood pressure before ischemia, ST-segment depression was invariably associated with a parallel increase in these parameters, highly suggestive of cardiac sympathetic nerve activation. We conclude that: 1) The majority of ischemic events that occurred in patients with stable angina during normal daily activity were apparently not precipitated by an excessive increase in myocardial oxygen demand but rather by transient impairment of regional myocardial perfusion. 2) The observation that most ischemic events occur when the levels of sympathetic nerve activity are high suggests that the sympathetic nervous system may play a key pathophysiological role in this syndrome, as cardiac sympathetic nerve activation can both increase metabolic demand and impair myocardial perfusion. 3) beta-Blockers significantly reduced episodes of transient myocardial ischemia in these patients, primarily by reducing cardiac metabolic requirements. The possibility that sympathetically mediated coronary vasoconstriction may also be affected by these drugs needs further investigation.

Mutations in coagulation factors in women with unexplained late fetal loss.

BACKGROUND: Factor V and prothrombin-gene mutations are independent risk factors for venous thrombosis; it is debated whether a mutation in the gene encoding methylenetetrahydrofolate reductase, an enzyme involved in homocysteine metabolism, also increases the risk of venous thrombosis. Whether any of these mutations is associated with an increased risk of late fetal death is not known. METHODS: We studied 67 women with a first episode of unexplained late fetal loss (fetal death after 20 weeks or more of gestation) and 232 women who had had one or more normal pregnancies and no late fetal losses. All the women were tested for the presence of three gene mutations. Women with other thrombophilic conditions were excluded from the study. RESULTS: Eleven of the 67 women with late fetal loss (16 percent) and 13 of the 232 control women (6 percent) had either the factor V or the prothrombin mutation. The relative risks of late fetal loss in carriers of the factor V and prothrombin mutations were 3.2 (95 percent confidence interval, 1.0 to 10.9) and 3.3 (95 percent confidence interval, 1.1 to 10.3), respectively. Thirteen percent of the women whose fetuses died and 20 percent of the control women were homozygous for the mutation in the methylenetetrahydrofolate reductase gene (relative risk, 0.8; 95 percent confidence interval, 0.5 to 1.2). CONCLUSIONS: Both the factor V and the prothrombin mutations are associated with an approximate tripling of the risk of late fetal loss.

Thrombolytic therapy reduces the incidence of left ventricular thrombus after anterior myocardial infarction. Relationship to vessel patency and infarct size.

BACKGROUND: Controversial evidence exists as to whether thrombolytic therapy reduces the incidence of left ventricular thrombus in acute myocardial infarction and, if so, how this relates to successful reperfusion. METHODS: Four hundred and eighteen consecutive patients underwent echocardiography and coronary angiography within 3 weeks of an acute myocardial infarction. A dyssynergic score was calculated by analysing regional wall motion in 18 left ventricular segments. The infarct-related artery was considered patent if TIMI grade 2 or 3 flow and less than 90% stenosis were present. Retrograde perfusion by Rentrop's grade 2 or 3 collaterals was considered significant. RESULTS: Large anterior myocardial infarctions were associated with the highest prevalence (39%) of left ventricular thrombosis. Thrombus was also very frequent if the left anterior descending coronary artery was occluded and no collaterals to the infarct area were seen (75%). Anticoagulant therapy reduced the prevalence of left ventricular thrombus, regardless of whether the infarct-related vessel was patent or not. Conversely, in patients undergoing thrombolysis the incidence of left ventricular thrombosis was lower when the left anterior descending coronary artery was patent, and especially when an early creatine kinase peak, suggestive of reperfusion, was recorded (7%). Finally, the presence of left ventricular thrombosis was inversely related to the asynergy score. CONCLUSION: These observations suggest that the presence of left ventricular thrombus is related to the extent of myocardial damage. Thrombolytic therapy reduces thrombus probably by salvaging myocardium at risk.

Antihistaminic treatment of allergic rhinitis: a double-blind study with terfenadine versus dexchlorpheniramine.

A double-blind study was carried out in 65 patients with seasonal rhinitis to compare the effectiveness and tolerance of terfenadine and dexchlorpheniramine. Patients were allocated at random to receive treatment for 1 week with either 60 mg terfenadine twice daily or 2 mg dexchlorpheniramine maleate 3-times daily. Before and after treatment, patients underwent RAST and skin prick tests for reactivity to pollen and those who were positive also had rhinomanometric measurements made of nasal resistance. Diary cards were used by patients to record the severity of nasal obstruction, rhinorrhoea, sneezing, watery, irritated and red eyes, itching of the nose, throat and eyes, and cough. Details were also kept of the frequency and severity of any side-effects. Pollen counts were taken daily during the treatment period. The results showed that both terfenadine and dexchlorpheniramine produced good or excellent relief of the main symptoms in 78% and 73% of the patients, respectively. There was no significant correlation between the pollen count and reduced symptom severity. Both drugs produced a reduction in total nasal resistance but this was not significantly different from initial values, neither was there a significant difference between treatment. Terfenadine was well tolerated and side-effects incidence was significantly lower (p less than 0.01) than in patients treated with dexchlorpheniramine, particularly so with reference to drowsiness.

Epidemiology and natural history of hepatitis G virus infection in chronic hemodialysis patients.

UNLABELLED: Patients on chronic hemodialysis (HD) have recently been identified as having a high prevalence of hepatitis G virus (HGV) infection. The clinical significance of HGV in this population remains unclear, with no data available as to the acquisition and natural history of HGV infection in this group. AIMS: To assess the prevalence and risk factors of HGV in a large cohort of chronic HD patients, and to evaluate the incidence and clinical consequences of HGV over time in this population. METHODS: Paired sera from 292 patients undergoing chronic HD treatment in four units in the Los Angeles area were tested for HGV RNA before and after they had been on HD for a mean period of 9.7 +/- 1.9 months. HGV was tested by a single-step RT-PCR using two couples of primers located in two different portions (5'UTR, NS5a) of the genome. The amplified products were detected by hybridization with 5' biotin-labeled probes specific for each region. RESULTS: At study entry there were 50 HGV RNA-positive patients, thus the HGV prevalence was 17% (50/292). The multivariate analysis by ordinal logistic regression model showed association (p = 0.0013) between HGV RNA and the location of patients among the HD units. No other significant associations were observed. Three (3/50 = 6%) HGV RNA-positive patients at study entry and 3 (3/41 = 7%) at the end of the follow-up showed a mild increase of alanine aminotransferase (ALT) activity in absence of other apparent causes of liver damage. 35 (70%) out of 50 HGV viremic patients had persistently detectable viremia during the study period; 15 (30%) had non-persistently detectable HGV RNA in the second serum specimen. There was no significant difference between the patients with persistently detectable HGV RNA and those who showed non-persistently detectable HGV viremia with regard to demographic, clinical or virological features. Six patients without detectable HGV viremia at the start of the study showed de novo HGV infection during the follow-up, thus the HGV incidence was 3.07% per year. These individuals did not simultaneously acquire HBV or HCV markers; de novo HGV infection was not associated with other demographic, clinical or virological features. One (16.7%) out of 6 individuals with HGV acquisition had persistently raised ALT levels and chronic HBsAg positivity. The prevalence of HGV was 14% (41/292) at the end of the observation period. CONCLUSIONS: The prevalence of HGV in our HD population was high; HGV positivity was strongly associated with the location of HD patients among the units; some HD individuals with current HGV infection showed biochemical signs of liver disease without other apparent causes. De novo acquisition of HGV occurred within HD units in the absence of evident parenteral risk factors for HGV other than their presence in the HD environment. A large portion of HGV viremic patients showed non-persistently detectable HGV viremia during the study. Acquisition of HGV was not associated with a rise in ALT activity unlike prior experience with de novo HCV in HD patients. Further investigations are warranted to explain the modes of HGV acquisition and the clinical significance of HGV in th HD population.

Detection of de novo hepatitis C virus infection by polymerase chain reaction in hemodialysis patients.

Patients on chronic hemodialysis (HD) treatment have been identified by serological testing, including second- and third-generation enzyme-linked immunosorbent assay (ELISA), as a high-risk group for hepatitis C virus (HCV) infection. Previous studies have shown that de novo cases of HCV may occur in HD units in the absence of other parenteral exposures, which suggests the spread of HCV between patients. In addition, the reverse-transcription polymerase chain reaction (RT-PCR), which directly detects HCV virus, has identified HCV infection in chronic HD patients who are seronegative. The aim of this study was to determine the incidence of HCV infection detected by RT-PCR technology in a large cohort of chronic HD patients. One hundred and twenty chronic HD patients, HCV-negative by serological assays (second-generation ELISA) and molecular techniques (branched DNA and RT-PCR), were observed for a mean period of 9.5 months. They were tested monthly for serum alanine aminotransferase levels (ALT) and by second-generation ELISA. At the end of the follow-up period, they were again evaluated by branched DNA and RT-PCR testing. HCV RNA was detected in patients' sera by RT followed by PCR using two separate primer sets from the 5'-untranslated region of the HCV genome. Southern blot was performed using a digoxigenin-labeled probe. Two patients who had HCV RNA detectable by RT-PCR at the end of the follow-up period remained branched-DNA-negative. Thus, the incidence of de novo acquisition of HCV infection in the current investigation was 2.1% per year. In 1 patient RT-PCR positivity and anti-HCV ELISA seroconversion occurred. The 2nd patient remained anti-HCV ELISA-negative, although viremic. In both patients, the onset of positivity by RT-PCR was associated with a rise of ALT levels into the 'abnormal range' in our laboratory. In these 2 patients, de novo acquisition of HCV infection was observed in the absence of obvious parenteral risk factors other than their presence in the HD environment. In conclusion, de novo acquisition of HCV infection may be undetected by ELISA and branched-DNA assays. The need to monitor chronic HD patients by serial ALT testing is emphasized. RT-PCR should be incorporated into diagnostic testing for HCV infection in chronic HD patients. RT-PCR technology can identify HCV in HD individuals with raised ALT activity.

Quantitative assessment of HCV load in chronic hemodialysis patients: a cross-sectional survey.

UNLABELLED: Recent evidence has been accumulated showing that chronic hemodialysis (HD) patients have a very high prevalence of antibodies to hepatitis C virus (HCV). In contrast, there is little information addressing the virological characteristics of HCV infection in this population. AIM: To measure HCV viral load and to correlate this with demographic, biochemical, and clinical features of a large cohort of HCV-infected patients on chronic HD. METHODS: 394 chronic HD patients were tested by branched-DNA signal amplification assay, anti-HCV enzyme-linked immunosorbent assay 2.0, and on the basis of the aspartate aminotransferase/alanine aminotransferase (AST/ALT) activity. Multivariate analysis by ordinal logistic regression model was performed: age, gender, race, time on HD, allocation of the patients among the HD units, etiology of end-stage renal disease, HBsAg status, anti-HCV positivity, HCV genotype, and AST/ALT levels were independent factors, and viremic levels of HCV in serum were assumed as dependent variables. RESULTS: 88 (22.3%) patients showed serological and/or virological signs of HCV infection. 59 (15%) out of 394 had detectable HCV RNA in serum, the mean HCV load was 19.4 x 10(5) (95% CI, 6.06 x 10(7) to 6.2 x 10(4)) Eq/ml. According to the criteria suggested by others [J Infect Dis 1994;169:1219-1225], there were 8 (13.5%) individuals with high-titer viremia (>1 x 10(7) Eq/ml) in the subset of viremic patients. A small subset (8/394 or 2%) of individuals was seronegative, but viremic; 29 (7%) out of 394 were seropositive without detectable HCV RNA in serum. Univariate analysis showed that the frequency of anti-HCV positivity was significantly higher in viremic patients as compared with individuals with no detectable HCV viremia: 51/59 (86%) vs. 29/335 (8.6%), p = 0.0001. Serum AST and ALT levels were significantly higher in viremic patients than in individuals with no detectable HCV RNA in serum: 23.8 (95% CI 60.8-9.3) vs. 17.1 (95% CI 50.4-5.8) U/l (p = 0.009) and 14.4 (95% CI 48.9-4.3) vs. 9.8 (95% CI, 37.3- 2. 5) U/l (p = 0.008). Logistic regression analysis showed an association between HCV viremia and anti-HCV positivity (p = 0. 00001) and ALT activity (p = 0.01). CONCLUSIONS: Hepatitis C virus infection is highly prevalent in the HD population; the viral load is relatively low, and it was associated with elevated hepatic enzyme levels and anti-HCV positivity. No other clinical characteristics were associated with HCV RNA levels. Seronegative but viremic patients were also found. Longitudinal studies with long follow-up periods are necessary to evaluate the course of HCV load over time in this population.

Epidemiology of Helicobacter pylori in chronic haemodialysis patients using the new RIBA H. pylori SIA.

BACKGROUND: There are few data concerning the epidemiology of H. pylori in patients on chronic haemodialysis (HD) treatment. These surveys concerned small populations and were made with ELISA technique. However, ELISA-based assays do not differentiate between strains of H. pylori that are associated with ulcers. Recent literature reports that formation of ulcers correlates strongly with the expression of cytotoxin-associated protein (CagA) and vacuolating cytotoxin (VacA) of H. pylori. METHODS: A novel serological test (RIBA H. pylori strip immunoblot assay (SIA)) has been recently introduced, it uses the H. pylori lysate (Lys) along with two additional purified recombinant antigens derived from CagA and VacA of H. pylori. AIM: To study the epidemiology of H. pylori using RIBA H. pylori SIA among chronic HD patients and blood donors as a control group. In addition, the activity of H. pylori was analysed by immunoblot technique in a group of patients with documented ulcers and normal renal function. RESULTS: The prevalence of antibody towards H. pylori among HD patients, blood donors, and patients with documented ulcers was 56% (127/228), 53% (84/158), and 100%, (21/21) respectively; the difference was significant (P=0.0001). The frequency of anti-H. pylori-positive individuals was significantly higher in patients with documented ulcers than HD patients and blood donors, 21/21 (100%) vs 211/386 (55%), P=0.0001. The frequency of antibody to H. pylori in the HD population was significantly associated with race (P= 0.005); no relationship between anti-H. pylori antibody and numerous demographic, biochemical, and clinical features of patients was seen. The frequency of antibodies against virulent strains of H. pylori in HD patients and blood donors with H. pylori was 60% (76/127) and 61% (51/84) respectively; it was 86% (18/21) among individuals with documented ulcers. No significant difference among these three groups occurred. CONCLUSIONS: The frequency of antibody towards H. pylori by RIBA H. pylori SIA was high both in HD patients and blood donors; patients with documented ulcers and normal renal function had significantly higher frequency of anti-H. pylori antibody. The anti-H. pylori antibody rate among HD patients was strongly associated with race. The prevalence of antibody against virulent strains of H. pylori did not change among HD patients and control groups. Studies in large cohorts of HD patients with documented peptic ulcer disease are in progress.