Changes in blood CD8+ lymphocyte activation status and plasma HIV RNA levels during antiretroviral therapy.

OBJECTIVE: To analyse the relationship between CD8+ lymphocyte phenotype alterations and plasma HIV RNA levels in HIV-infected patients treated with the zidovudine-didanosine combination. METHODS: A total of 30 HIV-infected patients who had never received antiretroviral therapy and who were starting treatment with a combination of zidovudine and didanosine were prospectively studied. Multiparameter flow cytometric analysis of CD8+ lymphocytes and plasma HIV RNA determination were performed on day 0, day 15 and monthly from months 1 to 6. RESULTS: Patients were divided into three categories according to the time-course of plasma HIV RNA levels. In 14 patients, an early and sustained fall in plasma HIV RNA to below the detection limit (500 copies/ml) was observed; in 10 patients, the fall was transient; in six patients, plasma HIV RNA was always detectable (non-responders). The mean CD4+ lymphocyte gain was 120 x 10(6)/l at month 6 in sustained and transient responders, and 55 x 10(6)/l in non-responders. A significant fall in the proportion of CD8+ lymphocytes with an activated phenotype was observed only in the two groups of responders, and was higher in the sustained responders (CD38+HLA-DR+, -56.8%; CD38+CD45RO+, -54.0%; HLA-DR+CD45RO+, -48.4%; CD38+CD28-, -47.3%). CONCLUSION: A fall in the proportion of activated CD8+ lymphocytes is associated with the disappearance of HIV RNA from plasma during antiretroviral therapy. Undetectable plasma HIV RNA is not associated with a return to normal CD8+ lymphocyte activation status after 6 months of treatment, suggesting that viral replication persists in lymphoid tissues.

Evidence of mitochondrial impairment during cardiac allograft rejection.

NADH laser fluorimetry and mitochondrial oxigraphy were used to study myocardial oxidative energy metabolism during cardiac allograft rejection. Heterotopic cardiac transplantation was performed on Lewis rats; allografts (with Fischer rat donors) were compared with isografts (with Lewis rat donors). In vivo and in vitro assays were performed six days after transplantation. Myocardial NADH fluorescence was recorded in vivo from grafted hearts, at baseline; during brief, complete ischemia; and during reperfusion. Oxygen consumption of mitochondria isolated from both native and grafted hearts was determined. Neither baseline levels nor maximum ischemic levels of NADH fluorescence (F0 = k[NADH]) were found to be significantly different between allografts (0.45 +/- 0.05 to 0.87 +/- 0.10) and isografts (0.45 +/- 0.04 to 1.11 +/- 0.05). During recovery, the rate of fluorescence decrease was significantly lower in allografts than in isografts (0.024 +/- 0.001 vs. 0.038 +/- 0.002 delta F0.s-1, P less than 10(-3], indicating a lower rate of NADH reoxidation. In the presence of malate and glutamate substrates, mitochondrial O2 consumption was significantly lower in allografts than in isografts (30 +/- 9 vs. 100 +/- 15 nanoatoms O2. min-1.mg prot-1, P less than 10(-2]. These results indicate that mitochondrial oxidative metabolism was impaired during the rejection process. Such energy production disturbances may contribute to the dysfunction of rejecting hearts.

Prospective study of CD8+ lymphocyte activation in relation to viral load in HIV-infected patients with > or = 400 CD4+ lymphocytes per microliter.

To investigate the temporal relationship between CD8+ lymphocyte phenotypic alterations, the CD4+ T cell decline, and plasma HIV RNA levels during the natural history of HIV infection, 33 treatment-naive HIV-infected patients with > or =400 CD4+ cells/microl were studied prospectively for 3 years. During the study period, 20 patients remained untreated, and only 6 received more than 6 months of therapy. A significant relationship was found between changes in plasma HIV RNA and changes in the proportion of CD38+CD8+ cells. Conversely, the number of CD4+ T cells lost per year was strongly related to the increase in the proportion of CD28-CD8+ T cells. A strong relationship between mean yearly changes in CD4+ T cell numbers and changes in HIV RNA was also observed. CD4+ T cell changes were associated with changes in both viral load and CD8+ T cell activation. These results provide support for the use of both virologic and immunologic parameters for prognosis and management during HIV infection.

In situ NADH laser fluorimetry of rat fast- and slow-twitch muscles during tetanus.

To investigate the variations of oxidation-reduction status of fast- and slow-twitch muscles during intense contractions, we performed in situ NADH laser fluorimetry during 25-s tetanus in extensor digitorum longus (EDL) and in soleus (SOL) muscles of eight Sprague-Dawley rats anesthetized with pentobarbital sodium. At base line the compensated NADH fluorescence (F0) was not significantly different between EDL and SOL. In EDL, tetanic stimulation induced an increase of F0, which rapidly reached a plateau that was 124% over the base-line value and stable until the end of the stimulation. In SOL, after an initial shouldering there was a continuous increase of F0 until the end of tetanus, reaching 275% of the base-line value. After the stimulation the initial rate of recovery was significantly faster in SOL than in EDL. We conclude that during and after intense contraction the variation of NADH content vs. time can be evaluated by in situ NADH laser fluorimetry in different muscle types. This nondestructive method can be helpful to differentiate in situ the various physiological or pathological oxidative capabilities of skeletal muscles.

Effects of diclofenac on experimental streptococcal necrotizing fasciitis (NF) in rabbit.

Aggravation of necrotizing fasciitis (NF) by the administration of non-steroidal antiinflammatory drugs (NSAIDs) has recently been suggested. A rabbit model of streptococcal NF was used to study the effects of parenteral administration of an NSAID on NF evolution and outcome. Of 16 rabbits inoculated with a Streptococcus pyogenes suspension together with staphylococcal alpha toxin, 8 were treated with two doses of 4 mg/kg diclofenac on day 1 after inoculation. Clinical, bacteriological and histological studies were performed until day 10. Under our experimental conditions, NSAID treatment significantly limited NF extension. A specific inverse relationship between the extent of inflammation and bacterial density in NF lesions was observed on day 1 after inoculation in the treated group suggesting that the greater severity of NF in humans treated with an NSAID could be due to the therapeutic delay induced by the misleading clinical effects of the NSAID, and not to inhibition of antibacterial defence.

Otogenic meningoencephalitis induced by Streptococcus pneumoniae in gerbils.

OBJECTIVE: Study and development of a gerbil model of pneumococcal meningoencephalitis secondary to acute middle ear (ME) otitis. Preliminary data raised the hypothesis of a direct bacterial dissemination from the ME focus to the central nervous system. This infection pattern was examined. DESIGN: Animals were inoculated bilaterally by transbulla challenge with a serotype 3 strain of Streptococcus pneumoniae at various inoculum sizes. The incidence and course of meningeal complications were studied in relation to the course of ME otitis. RESULTS: After inoculation of 40 bacteria per ear, lethal meningeal complications occurred in 14 (29%) of 48 cases. A 76% rate (25 of 33 animals) of early meningeal involvement was observed after inoculation of 10(4) bacteria per ear. Actual involvement of brain was confirmed histologically for both infection schemes. Bacterial counts 20 to 22 hours after infection with the higher inoculum showed various phases of the extension of the ME infection to brain tissue, cerebrospinal fluid, and bloodstream. Bacterial counts in ME and brain tissue were strongly correlated (P < .001). Nine of the 25 animals with infection of the central nervous system had positive brain tissue cultures without bacteremia. CONCLUSION: Gradations in inflammatory aspects of the meninges and cerebral parenchyma, together with bacteriologic findings, indicate a primary invasion of meningeal spaces that can result in lethal encephalitis and septicemia. This model might be useful for preclinical therapeutic assays on pneumococcal meningeal complications, including infections due to strains with abnormal susceptibility to antibiotics.

[Effect of sinorphan, an endopeptidase inhibitor on severe congestive cardiac insufficiency]. / Effet du sinorphan, un inhibiteur des endopeptidases dans l'insuffisance cardiaque congestive sévère.

Sinorphan is a powerful inhibitor of enkephalinases or endopeptidases 24-11, enzymes implicated in the degradation of the atrial natriuretic factor (ANF). In healthy volunteers, it increases plasma concentrations of endogenic ANF and increases diuresis and natriuresis. In order to study the tolerance and biological effects of pharmacological increase of plasma concentrations of endogenic ANF in severe congestive cardiac failure, 12 patients (in functional Classes III or IV of the NYHA classification) were given a single oral dose of 10, 20 or 40 mg of Sinorphan. Sinorphan was clinically well tolerated. The diastolic blood pressure decreased slightly (- 10 +/- 9 mmHg) but significantly (p less than 0.05). Systolic blood pressure and heart rate were unchanged. Despite spontaneously high plasma ANF concentrations (on average 15 times higher than normal subjects), Sinorphan induced an additional increase of 80 to 100% of plasma ANF concentration compared to the initial values (p less than 0.01) with no dose-dependent response for the dosages used. The inhibition of plasma endopeptidase activity attained 47% at the 30th minute. Urinary cyclic GMP excretion increased by 30% at the second hour (p less than 0.05). In addition, a statistically non significant tendency to increase diuresis and natriuresis was observed. These results show that Sinorphan increases plasma ANF concentrations by inhibition of its degradation in severe congestive cardiac failure and that this increase seems to be associated with potentially beneficial biological changes. The concept of endopeptidase inhibition should constitute a new therapeutic approach in cardiac failure, a situation in which the ANF seems to exert a favourable effect.(ABSTRACT TRUNCATED AT 250 WORDS)

[Demonstration of abnormalities of myocardial mitochondrial oxygenation in cardiac graft rejection]. / Mise en évidence d'anomalies de l'oxydation mitochondriale myocardique au cours du rejet de greffe cardiaque.

Abnormalities of myocardial metabolism during acute rejection may be due to ischemia to primary metabolic changes related to rejection. An experimental study of heterotopic cardiac transplantation in the rat was undertaken to study myocardial mitochondrial oxidation during acute rejection. The receivers were Lewis rats and the donors Fischer (FL: allograft) or Lewis (LL: isograft) rats. The oxygen consumption of the mitochondria (VO2m) isolated from the transplanted and native hearts was measured by oxygraphy six days after transplantation. Using maleate and glutamate substrates, the VO2m of transplanted hearts was significantly lower than that of native hearts in the two groups of rats (FL, p less than 0.01; LL, p less than 0.01). In addition, the VO2m of FL allograft transplanted hearts was significantly lower than in the LL rats (30 +/- 9 vs 100 +/- 15 nanoatoms of oxygen/min.mg/prot, p less than 0.01) as was the VO2m of the native hearts (FL: 106 +/- 23 vs LL: 164 +/- 26, p less than 0.02). The respiratory control ratio (RCR) was significantly lower in the transplanted than in the native hearts in both the FL and LL groups (p less than 0.05 and p less than 0.01 respectively). The comparison of the RCR in the two groups (FL vs LL) showed no significant difference for transplanted or native hearts. Electron microscopy of transplanted (rejected or not) and native hearts showed no morphological abnormality of the mitochondria. The lower VO2m of the allograft group indicates a disturbance in the mitochondrial respiratory pathway during acute rejection.(ABSTRACT TRUNCATED AT 250 WORDS)

[In situ evaluation of tissue metabolism by laser fluorimetry]. / Evaluation in situ du métabolisme tissulaire par fluorimétrie laser.

Laser fluorimetry is a new technique which provides continuous information on tissue metabolism in situ and without destruction. For the moment, it is mainly applied to the study of changes in redox gradients in various organs, including the heart, brain, liver, kidney and skeletal muscle, in cases with imbalance between oxygen supply and oxygen consumption. Other metabolisms, such as that of the crystalline lens with incipient cataract, can also be investigated by this technique.

[Physiopathological and therapeutic values of experimental model of acute otitis media. Review of the literature]. / Intérêts physiopathologiques et thérapeutiques du modèle expérimental d'otite moyenne aiguë. Revue de la littérature.

The animal model of acute otitis media (AOM) has been widely used to study the pathophysiology and treatment of this disease. Different authors have demonstrated a both mechanic and immunologic role of concomitant viral infection in the pathogenesis of AOM. The specific immune response was found mainly local in otitis media due to S. pneumoniae and systemic with H. influenzae. Local and systemic complications are currently precise. This model was proved useful in pre-clinical evaluation of antimicrobial agents and development of vaccines.

Dependence of 2,3-DPG and oxygen affinity of haemoglobin on sex and pregnancy in the guinea-pig.

Oxygen half-saturation of blood (P50), 2,3-diphosphoglycerate concentration (2,3-DPG) and Bohr effect were determined in male, and nonpregnant and pregnant female guinea pigs, according to a randomized block design. P50 was significantly higher in the female group (26.3 Torr plus or minus 0.22 SEM) than in the male group (24.8 Torr plus or minus 0.26 SEM) and was significantly lower in both these groups than in the pregnant group (27 Torr plus or minus 0.35 SEM). This difference in oxygen affinity was explained by differences in 2,3-DPG: 1.08 plus or minus 0.02 SEM in males, 1.24 plus or minus 0.03 in non-pregnant females and 1.34 plus or minus 0.03 mol/mol HB in pregnant females P50, 2,3-DPG and haemoglobin concentrations were significantly correlated for the ensemble of the 3 groups. There was no significant difference in Bohr effect between the 3 groups.

Effect of increased dosages of amoxicillin in treatment of experimental middle ear otitis due to penicillin-resistant Streptococcus pneumoniae.

A gerbil model of acute middle ear otitis was used to evaluate the efficacy of increased dosages of amoxicillin in eradicating infection induced by penicillin-resistant Streptococcus pneumoniae. Three different strains were used: (i) a serotype 23 penicillin-susceptible strain; (ii) a serotype 23 penicillin-resistant strain (MIC of penicillin, 2 micrograms/ml); and (iii) a serotype 19 highly penicillin-resistant strain (MIC of penicillin, 4 to 8 micrograms/ml). Animals were inoculated bilaterally with 10(7) CFU per ear by transbulla challenge and treated 2 to 4 h postinfection by amoxicillin administrated subcutaneously. The course of the disease was monitored bacteriologically on days 2, 4, and 8 postinfection. The three strains had a similar pathogenicity in untreated animals in terms of the duration of the disease, bacterial counts in middle ear (ME) fluid, and systemic complications. Infection due to the penicillin-susceptible strain was cured after two injections of 2.5 mg/kg of body weight. No bacteria were recovered at day 2 after two injections at 10 and 25 mg/kg with the penicillin-resistant and highly penicillin-resistant strains, respectively. Under these experimental conditions, increased does of amoxicillin consistent with MICs were able to clear ME infection. Pharmacokinetic parameters of amoxicillin in serum and ME fluid were within the clinical range at the doses used in the study.

Intrauterine growth retardation leads to a permanent nephron deficit in the rat.

Intrauterine growth retardation (IUGR) was induced in Sprague-Dawley rats by partial artery ligation of one uterine horn in the mother on day 17 of gestation or by feeding the mother a 5% protein diet from day 8 of gestation. The controls were pups of the contralateral uterine horn or pups born to mothers fed a normal (22%) protein diet. The number of nephrons present at birth and the final number of nephrons in 2-week-old rats were counted throughout the entire kidney. The number of nephrons present at birth and the final number of nephrons were significantly correlated with birth weight for growth-retarded rats of both groups and their corresponding controls (P < 0.02 for the poorest correlation). Clearance experiments and morphometric studies of 2-week-old rats born to mothers with uterine artery ligation indicated that, despite a large compensatory hypertrophy of the nephrons in those animals born with a nephron deficit of about 30%, the overall renal function was impaired. We conclude that IUGR is accompanied by a nephron deficit which may not be fully compensated for within the first weeks after birth.

Evidence for humoral immunodepression in NO2-exposed mice: influence of food restriction and stress.

The effects of food restriction or 20 ppm NO2 exposure on humoral immunity were investigated in normal and adrenalectomized C57Bl/6 mice. The thymic and splenic weights of sham-operated mice were similarly diminished after 4 days of NO2 exposure or 4 days of food depletion. The responses of corresponding adrenalectomized mice were less depressed. Undernutrition induced lymphoid organ involution and corticosteroids were partly involved. Plaque-forming cells (PFC) per spleen and per 10(6) cells were markedly depressed after 4 days of NO2 exposure, but less so after food deprivation. The same significant suppression of PFC was observed in adrenalectomized groups. Depression of humoral immunity was independent of stress-induced endogenous steroids. Moreover, NO2 had a specific effect on humoral immunodepression, food restriction being an associated factor.

Protective effects of ciprofloxacin against type II collagen induced arthritis in rats.

Ciprofloxacin, a new fluoroquinolone antibiotic, inhibits the in vitro production of interleukin 1 beta and tumor necrosis factor alpha by monocytes. We investigated its activity against type II collagen induced arthritis in rats. It exerted a dose dependent preventive effect at 50 and 75 mg/kg/day against clinical and histologic features of collagen induced arthritis without any influence on the production of anticollagen antibodies and alpha 1-acid glycoprotein. This effect was reversible after early removal of the treatment. Ciprofloxacin did not inhibit collagen induced arthritis in adrenalectomized rats but rather caused an exacerbation of the disease. Its effect was not modified by the simultaneous administration of an antiglucocorticoid, RU 40555.

Blood affinity for oxygen in experimental hemorrhagic shock with metabolic acidosis.

This study was designed to evaluate, in vivo, the effect of a severe non-respiratory acidosis on hemoglobin oxygen transport. Oxygen affinity of hemoglobin, Bohr effect, Hill's number and red cell 2,3-DPG were evaluated during experimental hemorrhagic shock in dogs. Three periods were considered: control, hypotension (mean arterial pressure 60 mm Hg for 2 hr 30 min) and blood replacement. There was no significant change in erythrocyte 2,3-DPG following hemorrhagic hypotension but ATP increased significantly. n, the Hill number (2.6), was not changed by in vivo acidosis (pH 7.1). Respiratory Bohr coefficient (BCO2) corresponding to pHe variations was drastically reduced (control BCO2 = 0.55, acidosis BCO2 = 0.31, blood replacement BCO2 = 0.35). P50(7.4) was not modified significantly by hemorrhagic acidosis. It is unlikely that variations of blood affinity for oxygen play a major role in oxygen delivery during early experimental hemorrhagic shock.

[Hemoglobin oxygen transport during experimental acute hypercapnia (author's transl)]. / Transport de l'oxygène par l'hémoglobine au cours de l'hypercapnie aigue experimentale

The effects on hemoglobin oxygen transport of acute respiratory acidosis have been studied in dogs inhaling a gaseous mixture with 12% CO2 (O2 21%) for two to five hours. In a first series of experiments, it was shown that the shape of the oxyhemoglobin dissociation curve (ODC) was not modified by severe acidosis (pH congruent to 7) lasting for two and a half hours. The Hill number (N equals 2.6) did not change significantly. The aim of the second experimental series was to stuey the Bohr effect and the hemoglobin oxygen affinity (P50). The control value for the respiratory Bohr coefficient (B) was --0.54; neither after two hours (--0.52), nor after five hours of hypercapnia (--0.55) was it significantly modified. The P50 expressed at arterial pH was much increased in acidosis (congruent to 45 torr); when expressed at standard p/ 7.4, it was slightly but significantly decreased (congruent to 1 torr) at the fifth hour. At the same time there was a decrease (p smaller than 0.05) in the erythrocyte 2,3-DPG approaching 15 p. cent; on the other hand the ATP concentration did not change significantly. No significant individual correlation was found between P50(7.4), 2,3-DPG and mean hemoglobin corpuscular concentration. These results suggest that during severe respiratory acidosis neither a change in the shape of ODC, nor a change in Bohr effect do affect the hemoglobin oxygen transport. The main characteristic remains the decrease in oxygen affinity of hemoglobin, due to the erythrocyte [H+] increase induced by hypercapnia ; this phenomenon is observed as long as the 2,3-DPG decrease stays moderate.

Oxygen transport by haemoglobin. A comparison of whole blood, washed erythrocytes and haemoglobin solution.

The properties of haemoglobin oxygen transport were compared under three different conditions: red cell in its natural medium, i.e. plasma (whole blood), washed red cell and haemoglobin A, the former suspended, the latter solved in an iso-osmotic tris buffer. The oxygen haemoglobin affinity (expressed as P50) and the respiratory Bohr effect variations were studied with modified media and unchanged pH and 2,3-diphosphoglycerate (2,3-DPG) concentration. Provided they are refered to intra-erythrocytic pH, none of these values were changed when varying environment. These results suggest that the three major ligands (H+ ions, 2,3-DPG and CO2) interaction with haemoglobin is largely predominant upon other factors which would interfere, and can completely account for oxygen transport by haemoglobin.