Enzymatic gelation to prepare chitosan gels: Study of gelation kinetics and identification of limiting parameters for controlled gel morphology.

Chitosan gels with well-controlled morphology were prepared by an enzymatic chitosan gelation process using in-situ production of ammonia through the urea enzymatic hydrolysis by urease. The reaction kinetics were studied by four complementary methods (rheological, colorimetric, flowing and pH-metric measurements) to define an advanced gelation pH (and the corresponding advanced gelation time) enabling to obtain homogeneous chitosan gels with well-controlled morphology and strong enough to be suitable for a future membrane preparation. A comparative study of chitosan gelation kinetics in water and aqueous chitosan solution highlighted differences mainly related to ammonia consumption when chitosan was present. The key parameters evidenced for the control of the gelation kinetics were the temperature and the urease concentration. The operating parameters required to elaborate gels with sufficient mechanical resistance to be handled from 2.5% w/v chitosan concentration were defined: a 3.5umL-1 urease concentration, a 75mM urea concentration and a temperature of 5°C.

Observation of A Raman mode splitting in few layer black phosphorus encapsulated with hexagonal boron nitride.

We investigate the impact of encapsulation with hexagonal boron nitride (h-BN) on the Raman spectrum of few layer black phosphorus. The encapsulation results in a significant reduction of the line width of the Raman modes of black phosphorus, due to a reduced phonon scattering rate. We observe a so far elusive peak in the Raman spectra ∼4 cm-1 above the A mode in trilayer and thicker flakes, which had not been observed experimentally. The newly observed mode originates from the strong black phosphorus inter-layer interaction, which induces a hardening of the surface atom vibration with respect to the corresponding modes of the inner layers. The observation of this mode suggests a significant impact of h-BN encapsulation on the properties of black phosphorus and can serve as an indicator of the quality of its surface.

Quantitative ultrasound at hand phalanges in adults with end-stage renal failure.

The aim of this study was to assess bone status in 220 subjects with end-stage renal failure (ESRF) (146 men, mean age 53.0 +/- 13.9 years and 74 women, mean age 48.1 +/- 14.3 years). The duration of hemodialysis (durHD) and duration of renal insufficiency (durRI) were, in men, 2.6 +/- 3.8 years and 7.7 +/- 8.0 years, and, in women, 2.8 +/- 3.4 years and 9.1 +/- 7.6 years, respectively. ESRF was caused by the following reasons: chronic glomerulonephritis in 92 patients, diabetes in 52, chronic pyelonephritis in 37, polycystic kidney disease in 19, amyloidosis in 5, hypertension in 4 and unknown cause in 11. The control group consisted of 1615 normal healthy subjects (1216 women, mean age 48.1 +/- 12.1 years and 399 men, mean age 52.9 +/- 14.8 years). Mean age did not differ between patients and controls. Skeletal status was evaluated by quantitative ultrasound (US) measurements at the hand phalanges using DBM 1200 (IGEA, Italy) which measures amplitude-dependent speed of sound (Ad-SoS, m/s). The mean value of Ad-SoS in male patients was 1981 +/- 88 m/s, T-score -l2.03 +/- 1.26, Z-score -0.53 +/- 1.7 and, in female patients, 1967 +/- 96 m/s, -2.23 +/- 1.37, -1.41 +/- 1.56, respectively. Respective values in male controls were 2008 +/- 81 m/s, -1.66 +/- 1.16, -0.01 +/- 0.98 and, in female controls, 2026 +/- 81 m/s, -1.4 +/- 1.15, -0.74 +/- 0.86, and were significantly higher than in male (p < 0.001) and female (p < 0.0000001) patients. A correlation analysis of Ad-SoS with durHD and durRI showed that only in males did both factors significantly influence parameters measured (r = -0.26, p < 0.01). Multiple stepwise regression analysis of Ad-SoS on age, durHD, durRI, weight and height was possible to perform only in males and the following equation was established: Ad-SoS = 2545 m/s - 3.09 x age (years) - 5.68 x durHD (years) - 2.15 x height (cm) - 0.99 x durRI (years), p < 0.000001, r = 0.55, SEE = 69.6. Concluding, in subjects with ESRF treated with hemodialysis, skeletal status assessed with the use of quantitative US was affected.

[Jan Kasprowicz's pattern of health and the cause of his death]. / Stan zdrowia i przyczyny smierci Jana Kasprowicza.

Jan Kasprowicz, one of the greatest Polish poets, was born in Szymborze, near Inowroclaw 1860. In his youth he often suffered from throat and upper respiratory track infections. When he was 64 he fell ill with diabetes and a stroke and hemiparesis. Insulin treatment in Lvow's clinic improved his condition, last two years later he suffered from an infarct, circulatory failure and arrhythmia. Progressive illness caused the poet's death on the 1st August 1926.

Anticonvulsant action of chlormethiazole is prevented by subconvulsive amounts of strychnine and aminophylline but not by bicuculline and picrotoxin.

The anticonvulsant action of chlormethiazole was evaluated with the use of subthreshold doses of convulsants affecting the purinergic, glycinergic and gamma-aminobutyric acid (GABA)-mediated transmission, i.e. aminophylline, strychnine, bicuculline and picrotoxin in the model of generalized tonic-clonic convulsions. Chlormethiazole protected mice against maximal electroshock-induced seizures with an ED50 of 130.8 mg/kg. Aminophylline (100 mg/kg) and strychnine (0.4 mg/kg) reversed the protective action of chlormethiazole against electroconvulsions raising the ED50 values of this drug to 218.6 and 208.6 mg/kg, respectively. In contrast, GABA antagonists, bicuculline and picrotoxin, neither affected the protection provided by chlormethiazole nor did they alter the protective activity of valproate, phenobarbital, diphenylhydantoin and carbamazepine against electroconvulsions. Our results indicate that (a) the anticonvulsant activity of chlormethiazole might be related to its interaction with strychnine-sensitive glycinergic as well as purinergic neurotransmission, (b) purinergic and strychnine-sensitive glycinergic events contribute more prominently than GABAergic ones to the anticonvulsant activity of the drugs providing protection against maximal electroshock-induced convulsions.

Quantitative ultrasound of phalanges and dual-energy X-ray absorptiometry of forearm and hand in patients with end-stage renal failure treated with dialysis.

The aim of the study was to evaluate the usefulness of quantitative ultrasound (QUS) measurement of the proximal phalanges of the hand in patients with end-stage renal failure (ESRF) treated with dialysis, and to compare results of this method with those from dual-energy X-ray absorptiometry (DXA) of hands and forearms (shaft and ultradistal site). Forty-one men aged 48.1 +/- 11.7 years and 31 women aged 43.1 +/- 12.3 years were examined. Mean QUS values of the hands in men and women with ESRF were significantly lower than the values of the healthy control group. There was a significant positive correlation between QUS and DXA of fingers, hands and also forearms, more pronounced in the shaft than in the ultradistal site. There was no significant difference in the measurements of extremities with or without a fistula. We conclude that QUS measurements are decreased in patients with ESRF treated with dialysis, and they correlate with DXA results. The simplicity of QUS makes it a valuable method in everyday practice. The clinical significance of the QUS results in these patients with ESRF treated with dialysis needs further investigation.

The benefits of hormone replacement therapy in pre-menopausal women with oestrogen deficiency on haemodialysis.

BACKGROUND: Impaired sexual function is an important cause of depression in uraemic females. Hyperprolactinaemia is frequent, and often associated with decreased serum oestradiol concentration, which can significantly contribute to accelerated bone loss. The aim of the study was to evaluate the effect of hormone replacement therapy (HRT) on sexual function, serum 17beta-oestradiol and prolactin, and bone mineral density (BMD) in pre-menopausal women undergoing haemodialysis. METHODS: Among 63 women on haemodialysis, aged 18-45 years, 23 with secondary amenorrhoea and serum oestradiol < 30 pg/ml were enrolled into the 1 year study. They were divided into: group I (n = 13) treated with transdermal oestradiol with cyclic addition of noretisterone acetate, and control group II (n = 10). BMD was measured with dual energy X-ray absorptiometry (DEXA). RESULTS: No important changes in sexual function and hormonal profile were observed in the control group, whereas in all women from group I the treatment induced regular menses and a marked improvement of libido and sexual activity. Serum 17beta-oestradiol increased after the first month from 20.5 +/- 11.7 to 46.8 +/- 13.6 pg/ml (P < 0.001) and remained at that level until the end of the study, accompanied by a decrease of serum prolactin (from 1457 +/- 1045 to 691 +/- 116 mIU/ml after 12 months; P < 0.001). In group I, the treatment induced an increase in BMD, although significant only in L2-L4 (P < 0.05), whereas in group II a mild insignificant decrease was observed. However, a comparison of BMD values after 12 months in both groups revealed marked (P < 0.01-P < 0.05) differences at all studied sites. CONCLUSIONS: Transdermal HRT allows sustained physiological serum oestradiol concentrations in pre-menopausal women with oestrogen deficiency on haemodialysis, with the restoration of regular menses and a marked improvement in their sexual function. The treatment inhibits bone demineralization and can play an important role in the prevention of early osteoporosis in this group of patients.

[The prevention of bone mineral loss with hormonal replacement therapy in premenopausal women on dialysis with estrogen deficiency]. / Hormonalna terapia zastepcza w zapobieganiu utracie mineralu kostnego u kobiet w wieku rozrodczym z niedoborem estradiolu leczonych powtarzanymi dializami pozaustrojowymi.

In 25-30% of premenopausal dialysis women low serum estrogen concentrations are observed. This "premature menopause" can significantly contribute to accelerated bone loss. The aim of the study was to evaluate the effect of estrogen-gestagen replacement therapy on bone mineral density (BMD) in hemodialysis women with secondary to uremia estrogen deficiency. Among 20 hemodialysis women, aged 18-45 years, with serum 17 beta-estradiol < 30 pg/ml, ten (group I) received transdermal estradiol with cyclic addition of noretisterone acetate (Estracomb TTS 50/0.25), and another ten formed the control group (group II). BMD was evaluated by dual photon x-ray absorptiometry (DEXA, Lunar) in: lumbar spine (L2-L4), 1/3 distal radius and femoral neck, before and after the study. Serum 17 beta-estradiol concentrations were measured before, and after 1, 3, 6 and 12 months of the study. After one year, in group I, in which serum 17 beta-estradiol normalized already during the first month (p < 0.001), an increase of in BMD was noted, although significant only in L2-L4 (p < 0.05). In group II, no change in serum 17 beta-estradiol and mild but insignificant decrease in BMD were observed. However, a comparison of BMD values after 12 months in both groups revealed the marked differences in all studied sites (p < 0.01, p < 0.02, p < 0.05 in L4-L2, distal radius and femoral neck, respectively). The mean serum calcium, phosphate, PTH and alkaline phosphatase activity were similar in both groups and did not change during the study. In premenopausal hemodialysis women with estrogen deficiency, hormonal replacement therapy inhibits bone demineralization and can be useful in prevention of early osteoporosis.

Effect of sleep deficit, knowledge of results, and stimulus quality on reaction time and response force.

Some recent findings suggested that response force measured during reaction time experiments might reflect changes in activation. We performed an experiment in which the effect of sleep deprivation, knowledge of results, and stimulus quality on response force was studied in simple and choice reaction tasks. As expected, both simple and choice reaction times increased with sleep deficit. Further, simple and choice reactions were faster with knowledge of results and slowed down when stimulus quality was degraded. As sleep deprivation affects both arousal and activation, we expected a detrimental effect of sleep on force amplitude. On the other hand, knowledge of results was expected to increase force by its compensatory effect on arousal and activation. No effect of sleep deprivation on response force was found. Knowledge of results increased response force independently of sleep deprivation.

HIV and tuberculosis infection in San Francisco's homeless adults. Prevalence and risk factors in a representative sample.

OBJECTIVE: To determine the prevalence and risk factors for human immunodeficiency virus (HIV) and tuberculosis (TB) infection and investigate the relationship between these two infections in homeless adults. DESIGN: Cross-sectional study. SETTING: Inner-city shelters and free meal programs. PARTICIPANTS: A representative sample of 1226 adults (> or = 18 years) were enrolled from community sites. MAIN OUTCOME MEASURES: Serum HIV-1 antibody status and tuberculin skin test reactivity. RESULTS: Human immunodeficiency virus seroprevalence was 8.5% (95% confidence interval [CI], 7.0% to 10.1%) and the prevalence of TB infection was 32% (95% CI, 30% to 37%). Nineteen percent of the HIV-seropositive subjects had positive tuberculin skin tests. Independent risk factors for HIV infection included younger age, black race, male homosexual contact, injection drug use, use of injection drugs in shooting galleries, and selling sex. Tuberculosis infection was associated with the duration of homelessness and living in crowded shelters or single-room-occupancy hotels. Injection drug use, a risk factor for HIV, was also a risk factor for TB, with a particularly strong association in women. No evidence of an association between TB and HIV infection was found, even after accounting for anergy. CONCLUSIONS: The homeless population in the United States should be considered a group at high risk for HIV infection and TB. Given the constellation of risk factors present, the high prevalence of infection, and lack of access to medical services, we anticipate that these communicable diseases in this population will represent a growing public health problem.

[Antithrombotic activity of low molecular weight heparin (enoxaparin) during hemodialysis in patients with terminal kidney failure]. / Przeciwzakrzepowe dzialanie niskoczasteczkowej heparyny (enoksaparyny) w czasie hemodializy u pacjentów ze schylkowa niewydolnoscia nerek.

The aim of the study was to evaluate the efficacy of low molecular weight heparine (enoxaparin) in comparison to heparin during haemodialysis (HD) in prevention of blood clotting chestry extracorporeal circulation. Enoxaparin (Clexan, Rhone-Poulenc Rorer, in syringes, 20 mg) was evaluated in 42 patients with end stage renal failure treated with HD. In the first part of study heparine and in the second part enoxaparin given into arterial lines were evaluated during 6 following HD with the same type of dialysator. Clotting of extracorporeal circulation and bleeding time from the needle site after HD were evaluated. Activated partial thromboplastin time (APTT) before, after 1 hour of HD and after HD during heparine and enoxaparin were measured. There was advantage of enoxaparin in 23 patients when compared to heparine. It was depended on the reduction of number of injections of enoxaparin when compared to heparine (22 patients have received heparine in 2 or more doses when only 5 patients have received enoxaparin in 2 doses) on the reduction of clotting events in extracorporeal circulation (16 events during heparine treatment -6.3% of all HD and 5 events during enoxaparin treatment -2.0% of all HD), and on the shortening of the bleeding time from the needle site after HD (5.9 +/- 3.4 min. during heparin and 4.5 +/- 1.6 min. during enoxaparin treatment; p < 0.02). Increase of APTT after 1 hour of HD when compared to the value from before HD was significantly lower during enoxaparin than heparine therapy (1.73 +/- 0.4 and 2.55 +/- 0.91 respectively; p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of two preservation solutions for erythrocyte transfusions in newborn infants.

To determine whether one of the newer preservation solutions for packed red blood cells (PRBC) is safe and effective in the transfusion of the very low birth weight infant, we conducted a randomized trial comparing PRBC preserved with the anticoagulant solution mannitol-adenine-dextrose (AS-1) and PRBC preserved with citrate-phosphate-dextrose-adenine (CPDA-1). Sixteen infants (birth weight 863 +/- 218 gm) with a gestational age of 26 +/- 3 weeks received one to three small-volume replacement transfusions with PRBC, 17 ml/kg, preserved with either AS-1 or CPDA-1 in a double crossover design. Transfusion with AS-1-preserved PRBC resulted in an equivalent increase in hemoglobin concentration when adjustment was made for the difference in the hemoglobin concentration of the transfused PRBC. During the transfusion, the percentage decrease in serum glucose values was greater with the CPDA-1 preservative than with the AS-1 preservative (54% +/- 13% vs 42% +/- 11% at 1 hour; p < 0.001). No other significant difference in blood chemistry values was found. Urine output was unaffected by AS-1 in the posttransfusion period. We conclude that (1) small-volume PRBC transfusions with AS-1 can be used in the very low birth weight infant without apparent detriment, (2) AS-1-preserved cells are as effective as cells preserved with CPDA-1 for increasing hemoglobin concentration, and (3) the higher dextrose content of the AS-1-preserved blood allows for improved glucose homeostasis during transfusion.

[Reversible renal failure in female patients with acute interstitial nephritis caused by cloxacillin]. / Odwracalna niewydolnosc nerek u chorej z ostrym sródmiazszowym ich zapaleniem wywolanym kloksacylina.

Cloxacillin was not listed as one of the drugs causing the acute interstitial nephritis, yet. A case of a 50-year female patient treated with cloxacillin is presented. Therapy was followed by nausea, vomiting, myalgia and arthralgia, and the symptoms of the acute renal failure which completely diminished after prednisone therapy despite of co-existing peptic ulcer. Low doses of corticosteroids seem helpful in the treatment of the acute interstitial nephritis following therapy with cloxacillin even after a long time of the onset.

Influence of different methylxanthines on the anticonvulsant action of common antiepileptic drugs in mice.

The protective activity of carbamazepine (CBZ, 60 min before testing), phenobarbital (PB, 120 min), phenytoin (PHT, 120 min), and valproate (VPA, 30 min) alone or concurrent with methylxanthine derivatives was evaluated against maximal electroshock-induced seizures (MES) in male mice. All drugs were administered intraperitoneally (i.p.), and the protection offered by antiepileptic drugs (AEDs) was expressed as ED50 in mg/kg. Caffeine sodium benzoate in doses of 0.0595-0.476 mmol/kg (11.55-92.4 mg/kg) distinctly reduced the anticonvulsant efficacy of PB, in the highest dose tested with an increase in ED50 value from 19.5 to 38 mg/kg. This methylxanthine derivative in the dose range of 0.119-0.476 mmol/kg (23.1-92.4 mg/kg) also efficiently inhibited the protective action of PHT. When combined with caffeine (0.238 and 0.476 mmol/kg), the ED50 of PHT was raised from 12 to 17 and 24 mg/kg, respectively. In doses of 0.238 and 0.476 mmol/kg, caffeine also diminished the efficacy of CBZ and VPA, and at the highest dose tested the methylxanthine elevated the respective ED50s from 13 to 20.5 mg/kg and from 270 to 420 mg/kg. Generally caffeine sodium benzoate (up to 0.476 mmol/kg) did not affect the plasma levels of studied AEDs, and only at 0.476 mmol/kg did it significantly decrease the level of PHT. Among the other methylxanthines, pentoxifylline (0.238-0.476 mmol/kg; 66.3-132.5 mg/kg) and diprophylline (0.952 mmol/kg; 242.1 mg/kg) inhibited the protective potential of PHT and the respective ED50s were raised from 12 to 16.5, 15.5, and 14 mg/kg. No significant alterations in PHT plasma levels were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

[Mannitol for the prevention of decompensation symptoms in hydrated patients undergoing long-term hemodialysis]. / Mannitol w zapobieganiu objawom zespolu niewyrównania u chorych przewodnionych, dlugotrwale dializowanych.

Symptoms of decompensation syndrome were frequently noted during sequential ultrafiltration/hemodialysis. In 9 adult patients chronically dialysed 101 cases of overhydration were seen. Mannitol was administered in a 20% solution (250 ml) in a continuous intravenous infusion during 49 dialyses. Changes in body weight were measured, arterial blood pressure, pulse rate, hematocrit, total plasma protein levels, urea, creatinine, sodium and potassium were determined as well as plasma osmolality. Mannitol significantly decreased muscular contractions during dialysis, weakness after dialysis, and incidence of various symptoms of decompensation. The values of analysed clinical parameters and laboratory tests did not differ from those determined without mannitol. Plasma creatinine, total plasma protein levels and hematocrit were significantly lower after several hours after the end of ultrafiltration/hemodialysis. We suggest that mannitol decreases the incidence of the symptoms of decompensation syndrome and is safe. Beneficial effect of mannitol is most probably produced by the changes in body fluids distribution.

Recovery of function after hip fracture. The role of social supports.

Previous studies have found that social support may reduce mortality after myocardial infarction and reduce overall mortality among the elderly. To determine whether social support also influences the recovery of function among patients who have had hip fractures and to describe other potential predictors of recovery after hip fracture, 111 patients with hip fractures were interviewed and examined before discharge from the hospital. The functional status of surviving patients was assessed again 6 months later. Patients who had a greater number of social supports had more complete recovery of their prefracture level of function (r = .21; P = .04). This association was strongest for patients over 60 years old (r = .31; P = .006); among these patients, this association remained statistically significant after adjustment for other significant (P less than .05) predictors of recovery: arm strength, mental status, and serum albumin. Additional studies should be done to test whether interventions to increase social supports can improve the recovery of function among elderly patients with hip fractures and other illnesses. In the meantime, health professionals should counsel elderly patients about the potential rehabilitative and preventive benefits of social supports.