The influence of a taurine containing drink on cardiac parameters before and after exercise measured by echocardiography

To determine the effect of the taurine containing drink "Red Bull" on cardiac parameters thirteen endurance trained subjects performed an exhaustive bout of endurance exercise at three different times. Prior to the exercise the original "Red Bull" drink, a similar drink without taurine, containing caffeine, and a "placebo" drink without caffeine and without taurine were ingested by the subjects in a double-blind cross-over design. Echocardiographic examinations were performed before the drinks, 40 minutes after the drinks prior to the exercise and in the regeneration period after exercise. Stroke volume was significantly influenced only in the "Red Bull group" (80,4+/-21,4 ml before drink vs. 97,5+/-26,2 ml in the regeneration period), mainly due to a reduced endsystolic diameter and volume. Furthermore in this group the peak late diastolic inflow (V(A)) in the regeneration period was significantly higher compared with the pre-exercise levels. This observation was also made in the caffeine group but without any consequences on ventricular function. The results of the present study show an influence of the original caffeine and taurine containing drink (Red Bull) on parameters of the cardiac contractility.

Ontogeny of rabbit proximal tubule urea permeability

Urea transport in the proximal tubule is passive and is dependent on the epithelial permeability. The present study examined the maturation of urea permeability (P(urea)) in in vitro perfused proximal convoluted tubules (PCT) and basolateral membrane vesicles (BLMV) from rabbit renal cortex. Urea transport was lower in neonatal than adult PCT at both 37 and 25 degrees C. The PCT P(urea) was also lower in the neonates than the adults (37 degrees C: 45.4 +/- 10.8 vs. 88.5 +/- 15.2 x 10(-6) cm/s, P < 0.05; 25 degrees C: 28.5 +/- 6.9 vs. 55.3 +/- 10.4 x 10(-6) cm/s; P < 0.05). The activation energy for PCT P(urea) was not different between the neonatal and adult groups. BLMV P(urea) was determined by measuring vesicle shrinkage, due to efflux of urea, using a stop-flow instrument. Neonatal BLMV P(urea) was not different from adult BLMV P(urea) at 37 degrees C [1.14 +/- 0.05 x 10(-6) vs. 1.25 +/- 0.05 x 10(-6) cm/s; P = not significant (NS)] or 25 degrees C (0.94 +/- 0.06 vs. 1.05 +/- 0.10 x 10(-6) cm/s; P = NS). There was no effect of 250 microM phloretin, an inhibitor of the urea transporter, on P(urea) in either adult or neonatal BLMV. The activation energy for urea diffusion was also identical in the neonatal and adult BLMV. These findings in the BLMV are in contrast to the brush-border membrane vesicles (BBMV) where we have previously demonstrated that urea transport is lower in the neonate than the adult. Urea transport is lower in the neonatal proximal tubule than the adult. This is due to a lower rate of apical membrane urea transport, whereas basolateral urea transport is the same in neonates and adults. The lower P(urea) in neonatal proximal tubules may play a role in overall urea excretion and in developing and maintaining a high medullary urea concentration and thus in the ability to concentrate the urine during renal maturation.

Ventriculo-peritoneal shunt and breast carcinoma

Ventriculo-peritoneal (V-P) shunt is a frequently performed surgical procedure for treating hydrocephalus. The incidence of breast carcinoma in the UK is 20,000 cases per year. We present a case of a patient with breast carcinoma in association with V-P shunt.

Role of glucocorticoids in the maturation of the rat renal Na+/H+ antiporter (NHE3)

BACKGROUND

Neonates have a lower Na+/H+ antiporter activity on the apical membrane of proximal tubule than that of adults. The maturational increase in Na+/H+ antiporter activity occurs at the time when there is a rise in serum glucocorticoid levels in rats. The purpose of the present study was to examine whether glucocorticoids are responsible for the postnatal increase in Na+/H+ antiporter activity.

METHODS

Nine-day-old Sprague-Dawley rats were compared with rats studied at 30 days of age who had either a sham operation or adrenalectomy (ADX) at nine days of age and with rats that had an adrenalectomy and physiologic corticosterone replacement (ADX-Cort) to determine whether glucocorticoid deficiency prevented the maturational increase in Na+/H+ antiporter activity. Na+/H+ antiporter activity was measured in proximal convoluted tubules perfused in vitro by the change in cell pH (pHi) following luminal sodium removal. NHE3 mRNA abundance was measured using Northern blot analysis, and NHE3 protein abundance was measured by immunoblot.

RESULTS

Na+/H+ antiporter activity was 93.8 +/- 17.7, 157.0 +/- 18.0, 356.7 +/- 29.9, and 402.5 +/- 14.5 pmol/mm. min in nine-day-old, ADX, ADX-Cort, and sham control groups, respectively. The ADX-Cort and sham control were higher than the 9-day-old and the 30-day-old ADX group (P < 0.05). Brush-border membrane NHE3 protein abundance in the nine-day-old and ADX groups were sixfold less than ADX-Cort and sham control groups (P < 0.001). Nine-day-old neonates had fivefold less renal cortical NHE3 mRNA than the ADX, ADX-Cort, and sham-operated control groups (P < 0.01).

CONCLUSIONS

These data demonstrate that glucocorticoids play a role in the postnatal maturation of the proximal tubule Na+/H+ antiporter activity and brush-border membrane NHE3 protein abundance. Glucocorticoid deficiency does not completely prevent the maturational increase in Na+/H+ antiporter activity and does not affect NHE3 mRNA abundance.

Thiazide diuretics arrest the progression of nephrocalcinosis in children with X-linked hypophosphatemia

OBJECTIVE

X-linked hypophosphatemia (XLH) is characterized clinically by rickets, hypophosphatemia, and hyperphosphaturia. Conventional treatment of XLH with oral phosphate and vitamin D is associated with increased urinary calcium excretion and nephrocalcinosis. Thiazide diuretics decrease urinary calcium excretion. The objective of this study was to determine the effect of thiazide diuretics on the clinical and radiologic course of nephrocalcinosis in children with XLH.

METHODS

The effect of hydrochlorothiazide (HCTZ) on clinical and radiologic progression of nephrocalcinosis was evaluated in 11 children with XLH. All patients had been treated previously with vitamin D and oral phosphate and had radiologic evidence of nephrocalcinosis. The average age of the patients at the start of HCTZ was 6.6 +/- 1.0 years. The effect of oral HCTZ at 0.8 +/- 0.1 mg/kg body weight per day given for 3.3 +/- 0.6 years on the progression of nephrocalcinosis and urinary calcium excretion was evaluated.

RESULTS

There was no change in serum phosphorous, calcium, potassium, and chloride after HCTZ therapy. HCTZ therapy increased serum bicarbonate and decreased urinary calcium excretion. The grade of nephrocalcinosis increased from 0.4 +/- 0.2 to 1.5 +/- 0.3 in the 2.3 +/- 0.3 years before initiation of HCTZ therapy, whereas the degree of nephrocalcinosis was stable after 3.3 +/- 0.6 years of HCTZ therapy (1.5 +/- 0.3 vs 3.0 +/- 0.3).

CONCLUSION

HCTZ decreased urinary calcium excretion but did not result in the resolution of nephrocalcinosis. However, when compared with the control period, HCTZ prevented the progression of nephrocalcinosis in children with XLH.

Metabolic activation of benzo[c]phenanthrene by cytochrome P450 enzymes in human liver and lung

The environmentally occurring polycyclic aromatic hydrocarbon (PAH) benzo[c]phenanthrene (B[c]PH) is a weak carcinogen in rodents. In contrast, the dihydrodiol-epoxides of B[c]PH are among the most carcinogenic PAH metabolites tested so far. In rodents, B[c]PH is predominantly metabolized to B[c]PH-5,6-dihydrodiol (B[c]PH-5,6-DH) and only to a minor extent to B[c]PH-3,4-DH, the proximate precursor of the highly potent ultimate carcinogen, B[c]PH-3,4-DH-1,2-epoxide. This might explain why in rodents B[c]PH is a weak carcinogen. However, little is known about human metabolism of B[c]PH. Using microsomal preparations from human liver and lung, we investigated the metabolic activation of B[c]PH. In contrast to the findings in experimental animals, human liver microsomes predominantly generated B[c]PH-3,4-DH and only to a minor extent B[c]PH-5,6-DH. Only one lung tissue sample was found to be metabolically active, producing B[c]PH-5,6-DH together with small amounts of B[c]PH-3,4-DH. Catalytic activities known to be associated with specific cytochrome P450 (P450) enzyme activities were determined and correlated with the spectrum of B[c]PH metabolites. The results indicate that B[c]PH-DH formation in human liver is mainly mediated by P450 1A2. Studies with P450 enzyme selective inhibitors confirmed these findings. Further support was obtained using preparations of the respective human recombinant P450 enzymes expressed in Escherichia coli and yeast. In addition to P450 1A2, P450 1B1 effectively mediated B[c]PH-metabolism. The umu-assay for induction of SOS repair response in Salmonella typhimurium TA 1535 pSK 1002 containing a umuC-lacZ reporter gene was used to study metabolic generation of genotoxic metabolites from B[c]PH-DHs in human microsomal preparations. B[c]PH-3,4-DH was activated by human liver microsomes to a potent genotoxic agent. Taken together, the results clearly demonstrate that human liver microsomes can effectively catalyze the biotransformation of B[c]PH into highly genotoxic metabolites. The results provide evidence that B[c]PH should be considered a potentially potent carcinogen in humans, and that rodent models may underestimate the risk.

Effect of prenatal dexamethasone on rat renal development

BACKGROUND

Prenatal insults can program the developing fetus to develop diseases that manifest in later life. Dexamethasone is often administered to the developing fetus to accelerate pulmonary development. The purpose of the present study was to determine whether prenatal dexamethasone adversely affects renal development and predisposes rats to develop renal disease and hypertension in later life.

METHODS

Pregnant rats were given either vehicle or two daily intraperitoneal injections of dexamethasone (0.2 mg/kg body weight) on gestational days: 11 and 12, 13 and 14, 15 and 16, 17 and 18, 19 and 20, or 20 and 21. Tail cuff blood pressure, glomerular number, and inulin clearance were measured in control and prenatal dexamethasone-treated rats when the rats were 60 to 90 days of age.

RESULTS

Prenatal dexamethasone did not affect the length of gestation, the number of animals per litter, or the total body weight or kidney weight measured at one day of age. Offspring of rats administered dexamethasone on days 15 and 16 gestation had a 30% reduction in glomerular number compared with control at 60 to 70 days of age (24,236 +/- 441 vs. 30,453 +/- 579, P < 0.01). Rats receiving prenatal dexamethasone on days 17 and 18 had an approximate 20% reduction in glomeruli compared with control (P < 0.01). Offspring of rats receiving dexamethasone on days 15 and 16 gestation had systolic blood pressures at 60 to 90 days of age that were higher than any other group (P < 0.05). The glomerular filtration rate was comparable in all of the groups.

CONCLUSIONS

This study shows that two daily doses of prenatal dexamethasone (0.2 mg/kg body weight) in rats do not produce intrauterine growth retardation. Adult offspring of rats that received prenatal dexamethasone during specific times of gestation have a reduced number of nephrons and hypertension.

The renal nerve is required for regulation of proximal tubule transport by intraluminally produced ANG II

The proximal tubule synthesizes and luminally secretes high levels of angiotensin II, which modulate proximal tubule transport independently of systemic angiotensin II. The purpose of this in vivo microperfusion study is to examine whether the renal nerves modulate the effect of intraluminal angiotensin II on proximal tubule transport. The decrement in volume reabsorption after addition of 10(-4) M luminal enalaprilat is a measure of the role of luminal angiotensin II on transport. Acute denervation decreased volume reabsorption (2.97 +/- 0.14 vs. 1.30 +/- 0.21 nl. mm(-1). min(-1), P < 0.001). Although luminal 10(-4) M enalaprilat decreased volume reabsorption in controls (2.97 +/- 0.14 vs. 1.61 +/- 0.26 nl. mm(-1). min(-1), P < 0.001), it did not after acute denervation (1.30 +/- 0.21 vs. 1.55 +/- 0.19 nl. mm(-1). min(-1)). After chronic denervation, volume reabsorption was unchanged from sham controls (2.26 +/- 0.28 vs. 2.70 +/- 0.19 nl. mm(-1). min(-1)). Addition of luminal 10(-4) M enalaprilat decreased volume reabsorption in sham control (2.70 +/- 0.19 vs. 1.60 +/- 0.10 nl. mm(-1). min(-1), P < 0.05) but not with chronic denervation (2.26 +/- 0.28 vs. 2.07 +/- 0.20 nl. mm(-1). min(-1)). Addition of 10(-8) M angiotensin II to the lumen does not affect transport due to the presence of luminal angiotensin II. However, addition of 10(-8) M angiotensin II to the tubular lumen increased the volume reabsorption after both acute (1.30 +/- 0.21 vs. 2.67 +/- 0.18 nl. mm(-1). min(-1), P < 0.05) and chronic denervation (2.26 +/- 0.28 vs. 3.57 +/- 0.44 nl. mm(-1). min(-1), P < 0.01). These data indicate that renal denervation abolished the luminal enalaprilat-sensitive component of proximal tubule transport, which is consistent with the renal nerves playing a role in the modulation of the intraluminal angiotensin II mediated component of proximal tubule transport.

Randomized trial of supplemental beta-carotene to prevent second head and neck cancer

Beta-carotene has established efficacy in animal models of oral carcinogenesis and has been shown to regress oral precancerous lesions in humans. The purpose of this study was to see whether these effects extended to the prevention of oral/pharyngeal/laryngeal (head and neck) cancer in humans. The subject population for this randomized, placebo-controlled, double-blinded clinical trial included 264 patients who had been curatively treated for a recent early-stage squamous cell carcinoma of the oral cavity, pharynx, or larynx. Patients were assigned randomly to receive 50 mg of beta-carotene per day or placebo and were followed for up to 90 months for the development of second primary tumors and local recurrences. After a median follow-up of 51 months, there was no difference between the two groups in the time to failure [second primary tumors plus local recurrences: relative risk (RR), 0.90; 95% confidence interval (CI), 0.56-1.45]. In site-specific analyses, supplemental beta-carotene had no significant effect on second head and neck cancer (RR, 0.69; 95% CI, 0.39-1.25) or lung cancer (RR, 1.44; 95% CI, 0.62-3.39). Total mortality was not significantly affected by this intervention (RR, 0.86; 95% CI, 0.52-1.42). Whereas none of the effects were statistically significant, the point estimates suggested a possible decrease in second head and neck cancer risk but a possible increase in lung cancer risk. These effects are consistent with the effects observed in trials using intermediate end point biological markers in humans, in which beta-carotene has established efficacy in oral precancerous lesions but has no effect or slightly worsens sputum cytology, and in animal carcinogenicity studies, in which beta-carotene has established efficacy in buccal pouch carcinogenesis in hamsters but not in animal models of respiratory tract/lung carcinogenesis, with some suggestions of tumor-promoting effects in respiratory tract/lung. If our results are replicated by other ongoing/completed trials, this suggests a critical need for mechanistic studies addressing differential responses in one epithelial site (head and neck) versus another (lung).

Perinatal renal ischemia resulting in hypertensive cardiomyopathy

Three neonates presented with malignant hypertension during the first week of life; 2 of them had congestive heart failure. Although none had indwelling umbilical artery catheters, unilateral renovascular lesions were diagnosed by nuclear perfusion scans. Angiotensin-converting enzyme inhibitor therapy produced rapid recovery. Hypertension must be included in the differential diagnosis of infants presenting with congestive heart failure and acidosis. Ultrasonography is not sensitive enough to exclude renovascular lesions. We emphasize the importance of early diagnosis and treatment.

Risky behaviour in Jamaican adolescent patients attending a sexually transmitted disease clinic

The prevalence of sexually transmitted diseases (STD) and risky behaviour patterns were studied in 165 adolescents attending a STD clinic in Jamaica. A standardised structured questionnaire, clinical algorithms for STD and serological tests for HIV and syphilitic infection were applied. High prevalences of risky behaviour including young age at onset of sexual activity, especially in boys, (mean age 12.5 +/- 2.5 years); unprotected sexual intercourse (only 4% used condoms consistently); multiple sexual partners (mean 3.8 +/- 2.4 and 1.8 +/- 1.2 for boys and girls, respectively) were found. Marijuana, used by 60% of the boys, was an independent risk factor for dysuria (adjusted Odds Ratio (OR), 2.0; 95% CI, 1.6-3.4). Repeated episodes of STD (33%), coinfection with HIV (1.2%), syphilis (1.2%) and teenage pregnancy (13%) were prominent findings. Educational strategies which promote behaviour intervention at an early age, frequent and consistent use of condoms, abstinence or delayed onset of sexual activity are essential to reducing the HIV/AIDS and STD risk in adolescents in Jamaica.

Effect of dipyridamole on serum and urinary phosphate in X-linked hypophosphatemia

X-linked hypophosphatemia (XLH) is characterized clinically by rickets, hypophosphatemia and hyperphosphaturia. Conventional treatment of XLH with oral phosphate and vitamin D is associated with hypercalcuria and nephrocalcinosis. Recently, intravenous and oral dipyridamole has been reported to decrease fractional excretion of phosphate in adults with idiopathic hyperphosphaturia. Our objective was to determine whether oral dipyridamole therapy reduces urinary phosphate excretion and increases serum phosphate concentration in children with XLH. A prospective study was performed in six children with XLH. The average age of the patients at the start of the study was 12.5+/-1.0 years. The effects of 12 weeks of oral dipyridamole therapy, at 4.4+/-0.4 mg/kg body weight per day, on serum phosphorous, parathyroid hormone (PTH), 1,25 (OH)2 vitamin D, osteocalcin, tubular maximum for phosphate reabsorption (TmP/GFR), urinary calcium excretion, and cyclic adenosine 3',5'-monophosphate (cAMP) excretion, were compared to baseline levels. Our results show that there was no change in serum phosphorous concentration or TmP/GFR after 12 weeks of dipyridamole therapy. Dipyridamole therapy also had no effect on serum PTH, serum 1,25 (OH)2 vitamin D, alkaline phosphatase, osteocalcin levels, urinary calcium or cAMP excretion. We therefore concluded that in children with XLH, a 12-week course of dipyridamole had no effect on serum phosphorous or its urinary excretion. Dipyridamole therapy is unlikely to improve the bone disease in children with XLH.

End-tidal carbon monoxide measurements in women with pregnancy-induced hypertension and preeclampsia

OBJECTIVE

We sought to compare the end-tidal carbon monoxide breath levels in pregnant women with and without pregnancy-induced hypertension and preeclampsia.

STUDY DESIGN

We prospectively performed end-tidal carbon monoxide measurements corrected for ambient carbon monoxide in nonsmoking women during late gestation (>31 weeks). The study group included 22 women with pregnancy-induced hypertension or symptoms of preeclampsia and a control group of 20 normotensive pregnant women.

RESULTS

The carbon monoxide measurements corrected for ambient carbon monoxide (mean +/- SD) were significantly lower (P <.01) in the hypertensive group than in the control group (1.17 +/- 0.35 vs 1.70 +/- 0.54 ppm). The study group had a significantly higher number of low (<1.2 ppm) end-tidal carbon monoxide measurements corrected for ambient carbon monoxide (13 [59.1%] vs 1 [5.0%]; P <.001). The end-tidal carbon monoxide measurements corrected for ambient carbon monoxide remained significantly lower in comparison with those found in the control group when the study group was divided into women with pregnancy-induced hypertension only (n = 11) and those with preeclampsia (n = 11) (1.19 +/- 0.37 ppm; P <.01; and 1.15 +/- 0.41 ppm; P <.01; respectively).

CONCLUSIONS

Our findings suggest that carbon monoxide formation may be significantly lower in women with pregnancy-induced hypertension and preeclampsia. These data suggest that carbon monoxide could have a contributory role in the apparent paradox of the seemingly protective effect of smoking to decrease the risk of preeclampsia.

Ontogeny of Na+/H+ antiporter activity in rat proximal convoluted tubules

Neonates have a lower serum bicarbonate level than adults, which is caused by a lower renal threshold for bicarbonate. Eighty percent of bicarbonate reabsorption occurs in the proximal tubule, in which proton secretion is predominantly mediated by a luminal Na+/H+ antiporter. Previous studies have demonstrated that there is a maturational increase in apical membrane rabbit proximal convoluted tubule Na+/H+ antiporter activity. However, in rat brush border membrane vesicles, Na+/H+ activity was higher in neonates than that in adult rats. To examine the maturation of Na+/H+ antiporter activity in rat proximal convoluted tubules, we perfused rat proximal convoluted tubules in vitro. Na+/H+ antiporter activity was assayed as the proton secretory rate on luminal sodium removal. Na+/H+ antiporter activity was 121.2 +/- 18.4 pmol/mm x min in neonatal and 451.8 +/- 40.6 pmol/mm x min in adult proximal convoluted tubules (p < 0.001). We next examined whether the increase in Na+/H+ antiporter activity was associated with changes in renal cortical NHE3 mRNA and brush border membrane NHE3 protein abundance. Adult renal cortical NHE3 mRNA abundance was 10-fold greater than that in 1-d-old neonates (p < 0.001). There was a comparable developmental increase in renal brush border membrane vesicle NHE3 protein abundance (p < 0.001). In summary, this study demonstrates that there is a maturational increase in rat apical membrane Na+/H+ antiporter activity, renal cortical NHE3 mRNA, and brush border membrane vesicle NHE3 protein abundance.

Kinesin-driven microtubule motility in the presence of alkaline-earth metal ions: indication for a calcium ion-dependent motility

We studied the effect of alkaline-earth metal ions on the kinesin-driven gliding of microtubules, using a narrow glass chamber enabling the exchange of buffer components without interrupting microscopic observation. Under standard conditions (0.5 mM Mg2+), microtubules were found to glide at a mean velocity of about 0.6 micron/s. Motility was widely ceased after removing Mg2+. Subsequent addition of Ca2+ restored motility (maximal mean gliding velocity measured: 0.26 micron/s at 2.5 mM Ca2+). Also in the presence of Sr2+ or Ba2+ a slow gliding could be observed (0.025 micron/s and 0.014 micron/s, respectively, at 0.5 mM). After removal of Ca2+, Sr2+, or Ba2+ and re-addition of Mg2+, the gliding velocities reached approximately the values determined under standard conditions. Motility was not changed when 0.5 mM Ca2+, Sr2+, or Ba2+ were applied together with Mg2+. Microtubule gliding stopped after substitution of 0.5 mM BeCl2 for Mg2+. When both BeCl2 and Mg2+ were present, the mean gliding velocity was reduced to 0.29 micron/s. In addition, many microtubules were released from the kinesin coated glass surface, indicating that the beryllium salt disorders the binding between kinesin and microtubules. Our results confirm that Mg2+ is the most suitable cofactor for kinesin driven microtubule motility. However, they also demonstrate that brain kinesin can generate motility when Ca2+ was substituted for Mg2+.

Effects of 20-HETE and 19(S)-HETE on rabbit proximal straight tubule volume transport

The kidney has the highest abundance of cytochrome P-450 of all extrahepatic organs. Within the kidney, the highest concentration of cytochrome P-450 is found in the proximal tubule. Whether 20- or 19(S)-hydroxyeicosatetraenoic acid (HETE), the major P-450 metabolites of arachidonic acid in the proximal tubule, affect transport in this segment has not been previously investigated. We examined the direct effects of 20- and 19(S)-HETE on volume absorption (J(v)) in the rabbit proximal straight tubule (PST). Production of 20-HETE by rabbit PST was demonstrated by incubating microdissected tubules with [(3)H]arachidonic acid and separating the lipid extract by HPLC. There was significant conversion of [(3)H]arachidonic acid to 20-HETE in control tubules that was inhibited by 10(-5) M N-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS). Addition of exogenous 20-HETE had no effect on PST volume transport. However, inhibition of endogenous production of 20-HETE using DDMS stimulated transport. In the presence of DDMS, 20-HETE inhibited PST J(v). 19(S)-HETE in the bathing solution stimulated PST J(v) alone and in the presence of DDMS. Thus omega- and omega-1-hydroxylase products of arachidonic acid have direct effects on PST transport. Endogenous production of 20-HETE may play a role in tonic suppression of transport and may therefore be an endogenous regulator of transport in the proximal tubule.

Genetic variation among populations of the Hessian fly Mayetiola destructor (Diptera: Cecidomyiidae) in Morocco and Syria

The RAPD-PCR technique was used to study genetic variation within and among geographical populations of the Hessian fly, Mayetiola destructor (Say), from Morocco and Syria, associated with the fly's ability to overcome resistance in three wheat cultivars containing H5, H13 and H22 resistance genes. Variation was detected both for the level of susceptibility of the cultivars and RAPD profiles of M. destructor populations. By the use of RAPD-PCR, high genetic variability was detected among individuals and populations of M. destructor within and between areas separated geographically. The DNA fingerprints of populations of M. destructor were area-specific with Nei's measures of genetic distance ranging from 0.156 (between Abda and Beni Mellal, Morocco) to 1.977 (between Marchouch, Morocco and Lattakia, Syria). Cluster analysis of the genetic distances among the populations, identified the Syrian population as an outlier. A highly significant correlation (r = 0.81) observed between the genetic and geographic distances among the populations, provided genetic support for dispersal of the fly from its presumed origin in West Asia to Morocco.

Developmental outcomes and cognitive functioning in infant and child heart transplant recipients

Pediatric heart transplantation has become a mainstay in the treatment of end-stage heart disease in infants and children. There is, however, sparse information on post-transplant developmental and cognitive functioning. At Loma Linda University Children's Hospital 223 infants have undergone heart transplantation surgery with a survival rate of 73% (n=165). This article reports on four areas of investigation of this cohort of infants. Infant development: Two studies were done utilizing the Bayley Scales of Infant Development (mean 100, S.D.+/-15). The first study (n=48) showed mean values within the normal range [Mental Development Index (MDI) 87; Psychomotor Developmental Index (PDI) 90]. The second study (n=23) showed developmental scores within normal limits in 4-8 month olds with a tendency for decline in development at 12-24 months (MDI 83, PDI 77). Child development: Ninty-one infant recipients were greater than 5 years old. Forty-five children were excluded because of long distances from the hospital, second transplantation, abnormal karyotype, primary language non-English, or invalid testing. The Wechsler Preschool and Primary Scale of Intelligence-Revised testing of 5-6-year-olds (n=23) showed a Full Scale IQ of 74, Performance IQ of 76, and Verbal IQ of 77. The Wechsler Intelligence Scale for Children-III testing of 7-10-year-olds (n=23) showed a Full Scale IQ of 86, Performance IQ of 89, and Verbal IQ of 86. The Wechsler Individual Achievement Test (mean 100, S.D.+/-15) yielded a Total Composite of 91, Mathematics Composite of 86, Language Composite of 98, and a Reading Composite of 94. Visual spatial skills: Visual motor integration (mean 100, S.D.+/-15) was evaluated in 5-10-year-olds with a mean of 87; however, 52% of the children had scores below 1 S.D. Subtests from the Wechsler scales that assess visual motor and visual spatial skills indicated significant deficits. Behavior: Younger children (n=33) demonstrated behaviors indicative of social isolation. Older children (n=36) showed behavior that was within the normal limits, but depression was noted in a significant number of them. Conclusions: Infant heart transplant recipients demonstrate IQ and achievement levels within the normal range, but there is a significant amount of variability with more children than would be expected scoring in the lower ranges. Children with heart transplantation are at risk for visual spatial skill deficits. Young children are at risk for social isolation while symptoms of depression are noted in older children.

Novel amiloride-sensitive sodium-dependent proton secretion in the mouse proximal convoluted tubule

The proximal convoluted tubule (PCT) reabsorbs most of the filtered bicarbonate. Proton secretion is believed to be mediated predominantly by an apical membrane Na(+)/H(+) exchanger (NHE). Several NHE isoforms have been cloned, but only NHE3 and NHE2 are known to be present on the apical membrane of the PCT. Here we examined apical membrane PCT sodium-dependent proton secretion of wild-type (NHE3(+/+)/NHE2(+/+)), NHE3(-/-), NHE2(-/-), and double-knockout NHE3(-/-)/NHE2(-/-) mice to determine their relative contribution to luminal proton secretion. NHE2(-/-) and wild-type mice had comparable rates of sodium-dependent proton secretion. Sodium-dependent proton secretion in NHE3(-/-) mice was approximately 50% that of wild-type mice. The residual sodium-dependent proton secretion was inhibited by 100 microM 5-(N-ethyl-N-isopropyl) amiloride (EIPA). Luminal sodium-dependent proton secretion was the same in NHE3(-/-)/NHE2(-/-) as in NHE3(-/-) mice. These data point to a previously unrecognized Na(+)-dependent EIPA-sensitive proton secretory mechanism in the proximal tubule that may play an important role in acid-base homeostasis.

Fission yeast homologs of human CENP-B have redundant functions affecting cell growth and chromosome segregation

Two functionally important DNA sequence elements in centromeres of the fission yeast Schizosaccharomyces pombe are the centromeric central core and the K-type repeat. Both of these DNA elements show internal functional redundancy that is not correlated with a conserved DNA sequence. Specific, but degenerate, sequences in these elements are bound in vitro by the S. pombe DNA-binding proteins Abp1p (also called Cbp1p) and Cbhp, which are related to the mammalian centromere DNA-binding protein CENP-B. In this study, we determined that Abp1p binds to at least one of its target sequences within S. pombe centromere II central core (cc2) DNA with an affinity (K(s) = 7 x 10(9) M(-1)) higher than those of other known centromere DNA-binding proteins for their cognate targets. In vivo, epitope-tagged Cbhp associated with centromeric K repeat chromatin, as well as with noncentromeric regions. Like abp1(+)/cbp1(+), we found that cbh(+) is not essential in fission yeast, but a strain carrying deletions of both genes (Deltaabp1 Deltacbh) is extremely compromised in growth rate and morphology and missegregates chromosomes at very high frequency. The synergism between the two null mutations suggests that these proteins perform redundant functions in S. pombe chromosome segregation. In vitro assays with cell extracts with these proteins depleted allowed the specific assignments of several binding sites for them within cc2 and the K-type repeat. Redundancy observed at the centromere DNA level appears to be reflected at the protein level, as no single member of the CENP-B-related protein family is essential for proper chromosome segregation in fission yeast. The relevance of these findings to mammalian centromeres is discussed.

Maturation of proximal straight tubule NaCl transport: role of thyroid hormone

We have recently demonstrated that the rates of both active and passive proximal straight tubule (PST) NaCl transport in neonatal rabbits were less than in adults. In this segment NaCl entry across the apical membrane is via parallel Na(+)/H(+) and Cl(-)/OH(-) exchangers, which increases in activity with maturation. The present in vitro microperfusion study examined whether thyroid hormone plays a role in the maturational increase in PST NaCl transport. Neonatal and adult PST were perfused with a high-chloride-low bicarbonate solution without organic solutes, simulating late proximal tubule fluid. Thyroid hormone-treated neonates had a higher rate of PST total and passive NaCl transport. In 8-wk-old animals that were hypothyroid since birth, the maturational increase in total and passive NaCl transport was prevented. Thyroid treatment for 4 days in hypothyroid 8-wk-old rabbits increased the rate of both total and passive NaCl transport. The maturational increases in both Na(+)/H(+) and Cl(-)/OH(-) exchange activities were blunted in 8-wk-old hypothyroid animals and increased to control levels with thyroid treatment. This study demonstrates that thyroid hormone is a factor responsible for the maturational increase in both active and passive PST NaCl transport.

Maturational changes in rabbit renal basolateral membrane vesicle osmotic water permeability

We have recently demonstrated that while the osmotic water permeability (Pf) of neonatal proximal tubules is higher than that of adult tubules, the Pf of brushborder membrane vesicles from neonatal rabbits is lower than that of adults. The present study examined developmental changes in the water transport characteristics of proximal tubule basolateral membranes by determining aquaporin 1 (AQP1) protein abundance and the Pf in neonatal (10-14 days old) and adult rabbit renal basolateral membrane vesicles (BLMV). At 25 degrees C the Pf of neonatal BLMV was significantly lower than the adult BLMV at osmotic gradients ranging from 40 to 160 mOsm/kg water. The activation energies for osmotic water movement were identical in the neonatal and adult BLMV (8.65 +/- 0.47 vs. 8.86 +/- 1.35 kcal x deg(-1) x mol(-1). Reflection coefficients for sodium chloride and sodium bicarbonate were identical in both the neonatal and adult BLMV and were not different from one. Mercury chloride (0.5 mM) reduced osmotic water movement by 31.3 +/- 5.5% in the adult BLMV, but by only 4.0 +/- 4.0% in neonatal vesicles (P < 0.01). Adult BLMV AQP1 abundance was higher than that in the neonate. These data demonstrate that neonatal BLMV have a lower Pf and AQP1 protein abundance than adults and that a significantly greater fraction of water traverses the basolateral membrane lipid bilayer and not water channels in neonates compared to adults. The lower Pf of the neonatal BLMV indicates that the basolateral membrane is not responsible for the higher transepithelial Pf in the neonatal proximal tubule.

Renal citrate metabolism and urinary citrate excretion in the infant rat

BACKGROUND

Although hypercalciuria has the same prevalence in children as adults, children rarely develop renal stones. This may be explained by a greater urinary citrate excretion in infants compared with adults. The present study examines the renal excretion of citrate and renal cortical citrate metabolism in infant and adult rats.

METHODS

Adult male and newly weaned infant rats were acclimated to metabolic cages and fed synthetic diets. Urine was collected after two days, and renal cortical citrate metabolism was assayed.

RESULTS

Infant rats had a lower plasma [HCO3-] and higher plasma [K+] and had a fourfold higher urinary citrate:creatinine ratio and a twofold higher concentration of citrate in their urine compared with adult rats. This higher urinary citrate excretion was not due to a difference in renal proximal tubular Na/citrate cotransporter activity, nor renal cortical citrate synthase or ATP citrate lyase activities in infants as compared with adults. However, infant rat kidneys had significantly lower mitochondrial aconitase (m-aconitase) activity. Renal cortical citrate concentrations were comparable in infant and adult rats. Manipulation of plasma [K+] to adult levels did not affect the higher urinary citrate excretion in infant rats.

CONCLUSIONS

Urinary citrate excretion in infant rats is greater than in adults but does not parallel tissue [citrate]. Thus, this higher urinary citrate is likely due to maturational differences in the proximal tubule, other than Na/citrate cotransport, that directly affect citrate transport.

A study of craniofacial growth in infant heart transplant recipients receiving cyclosporine

BACKGROUND

Cyclosporine is an effective immunosuppressive drug that has found widespread application in organ transplantation. However, a few studies have implicated cyclosporine as adversely affecting craniofacial growth in the pediatric population. The purpose of this study was to evaluate the possible untoward effects of cyclosporine long-term on craniofacial growth in a group of infant heart transplantation recipients.

METHODS

A prospective group (n = 28) of 18 Caucasian (white) children (9 female and 9 male, ages 4-10 years) and 10 Hispanic children (3 female and 7 male, ages 4-10 years) were evaluated. No attempt was made for either study group to delineate on individuals specific country of origin. None of the subjects had undergone orthodontic therapy. All subjects had heart transplantations before 6 months of age and followed the Loma Linda University International Pediatric Heart Transplantation Immunosuppression protocol. The primary immunosuppression agent was cyclosporine with azathioprine or methotrexate. Rescue therapy for graft rejection consisted of glucocorticoid and/or polyclonal antibody therapy. None of the subjects received the immunosuppressant tacrolimus (FK506). Using lateral cephalometric radiography, seven skeletal angular measurements (SNA, SNB, ANB, GoGn-SN, NA-Pog, ArGoMe, NPog-AB) were examined and compared to contemporary growth standards. Hand/wrist radiographs were evaluated for bone age. Also, longitudinal height, weight, and head circumference data was obtained and compared to standardized growth and development curves.

RESULTS

Descriptive statistics were used to summarize the data. Cephalometrically, 86% (N = 24), showed minor deviation from mean normative values. Four of the subjects (14%) exhibited cephalometric measures indicative of individuals with a vertical growth pattern. Analysis of the hand/wrist radiographs showed all but one subject to have normal bone age. Height, weight, and head circumference data revealed a wide range of growth percentiles for the entire group with mean percentiles in the range of 25% to 50%.

CONCLUSIONS

The findings of this pilot study indicated that, in general, skeletal growth of the craniofacial complex as well as axial skeletal growth was not statistically significantly altered by the immunosuppressive regimen of cyclosporine over the time period evaluated. Further longitudinal data of this study's subjects may shed more light on the possible adverse effects of cyclosporine on craniofacial growth and development in spite of the fact that no untoward correlation was found over the time period studied.

Symptomatic and asymptomatic chlamydial non-gonococcal urethritis in Jamaica: the potential for HIV transmission

To determine the contribution of Chlamydia trachomatis to non-gonococcal urethritis (NGU) in men attending sexually transmitted disease (STD) clinics in Jamaica we studied men with NGU (n=339), and control groups including asymptomatic men who were STD contacts (n=61), asymptomatic men who were not STD contacts (n=32) and men with gonococcal urethritis (GU) (n=61). Urethral specimens were examined for C. trachomatis and Neisseria gonorrhoeae. Serological tests for syphilis (STS) and HIV-1 infection were also performed. C. trachomatis accounted for 63% of cases of NGU but high prevalences were also found in asymptomatic STD contacts (59%), asymptomatic STD non-contacts (78%) and men with GU (48%). The prevalence of C. trachomatis in men with GU differed significantly from that in men with NGU and asymptomatic STD non-contacts (P<0.05). C. trachomatis infection in men with NGU was associated with multiple sex partners (71% vs 58%; chi2=4.78; odds ratio (OR)=1.76; P<0.05) and previous history of gonococcal infection (83% vs 42%; chi2=59.8; OR=6.8; P<0.0001). Concomitant infection with HIV-1 occurred in 5.2% of cases of NGU and 50% and 90%, respectively, of the HIV-positive men had chlamydia or reactive STS. As a cost effective strategy in the control of STD and HIV we recommend presumptive treatment for C. trachomatis in men seeking STD treatment in Jamaica.

Are randomized trials of hormone replacement therapy in symptomatic women with breast cancer feasible?

OBJECTIVE

To evaluate the feasibility of conducting a large randomized trial of HRT in symptomatic women with early-stage breast cancer.

DESIGN

Open randomized study.

SETTING

Outpatient clinics at The Royal Marsden and St. George's Hospitals, London.

PATIENT(S)

One hundred postmenopausal women with early-stage breast cancer, experiencing vasomotor symptoms and/or vaginal dryness.

INTERVENTION(S)

Randomization (1:1) to HRT or no HRT for 6 months.

MAIN OUTCOME MEASURE(S)

Acceptance, continuance rates, and the reasons eligible women declined study entry.

RESULT(S)

Acceptance (38.8%) and continuance rates (>80%) were encouraging. The efficacy of HRT did not appear to be antagonized with concomitant tamoxifen. Seventy-five percent of women continued HRT after the study ended. Three women developed metastatic disease. Two used HRT.

CONCLUSION(S)

Despite informed consent, a national UK randomized trial of HRT should be feasible and has now been planned. Successful implementation necessitates the provision of information about HRT and the estrogen deficiency side effects of breast cancer therapy to health professionals and women with breast cancer.

Effect of temperature on kinesin-driven microtubule gliding and kinesin ATPase activity

DeCuevas et al. [J. Cell Biol. 116 (1992) 957-965] demonstrated by circular dichroism spectroscopy for the kinesin stalk fragment that shifting temperature from 25 to 30 degrees C caused a conformational transition. To gain insight into functional consequences of such a transition, we studied the temperature dependence of a full-length kinesin by measuring both the velocity of microtubule gliding across kinesin-coated surfaces and microtubule-promoted kinesin ATPase activity in solution. The corresponding Arrhenius plots revealed distinct breaks at 27 degrees C, corroborating the temperature-dependent conformational transition for a motility-competent full-length kinesin. Microtubules were found to glide up to 45 degrees C; at higher temperatures, kinesin was irreversibly damaged.

Improving the Nutritional Quality and Yield Potential of Grasspea (Lathyrus Sativus L.)

Lathyrus sativus (grasspea or chickling pea) is a popular food and feed crop in certain Asian and African countries, such as Bangladesh, China, Ethiopia, India, Nepal, and Pakistan, because of its resistance to drought, flood, and moderate salinity and because of its low input requirements. When other crops fail under adverse climatic conditions, L. sativus can become the only available food source for the poor and sometimes is a survival food during famine. Although seeds of L. sativus are tasty and protein rich, overconsumption can cause an upper-neurone disease known as neurolathyrism, an irreversible paralysis of the lower limbs. The level of this compound in the dry seeds varies widely, depending on genetic factors and environmental conditions.

The ability of L. sativus to provide an economic yield under most adverse conditions has made it a popular crop in subsistence farming in many developing countries, and it offers a great potential for use in other parts of the world. In the West Asia and North Africa (WANA) region, under low-rainfall conditions there is a tendency for increasing monoculture of cereals, such as barley. The incorporation of grasspea in the rotation can make the production system more sustainable by improving soil fertility and breaking disease and pest cycles.

The objectives of the crop improvement programme of International Center for Agricultural Research in the Dry Areas (ICARDA) for this species are to improve its yield potential and nutritional quality through the reduction of its content of the neurotoxin 3-(N -oxalyl)-L-2,3-diaminopropionic acid (β-ODAP). Low-neurotoxin lines having 0.07% to 0.02% β-ODAP were developed by using conventional breeding methods and by developing somaclonal variants.

Acute vision loss in children with autosomal recessive polycystic kidney disease

Patients with autosomal recessive polycystic kidney disease (ARPKD) often present with renal insufficiency and hypertension. We present two children with ARPKD and end-stage renal disease who developed anterior ischemic optic neuropathy and vision loss. Anterior ischemic optic neuropathy occurs rarely in children and has never been reported in children with ARPKD or end-stage renal disease. Both of our patients were chronically hypotensive and anemic, which are known risk factors for ischemic optic neuropathy.

Setting up a breast cancer family history clinic

Breast cancer causes around 21,000 deaths per year in the UK, the vast majority of these occurring in women aged over 50 years with no genetic predisposition to the disease. Screening and symptomatic services for these women, although by no means perfect or homogeneous, have gradually improved over the last 10 years and, perhaps as a result of this, together with increased use of adjuvant systemic therapy, mortality in this group has fallen. Despite this reassuring state of affairs, media interest in the disease and patients' perception of their risk of developing breast cancer have risen. Part of this is undoubtedly due to the new scientific developments in cancer genetics and, in particular, identification of the BRCA1 gene in 1994 and BRCA2 gene shortly afterwards. These genes are dominantly inherited with up to 80% penetrance; thus, women (and occasionally men) inherit these genes and have a high lifetime risk of developing breast cancer, usually at a younger age than average and possibly of a more aggressive phenotype. Unaffected family members can now be screened and, if they prove carriers, screening for early detection and prevention strategies such as bilateral prophylactic mastectomy can be offered. Because of the high risk of ovarian cancer in BRCA1 carriers, screening or prophylactic ovariectomy may also be considered.

Contrast-enhanced colour Doppler ultrasonography in suspected breast cancer recurrence

BACKGROUND

Postoperative scarring and radiotherapy changes in the conservatively treated breast often mimic breast cancer recurrence, resulting in many unnecessary biopsies. Local breast cancer recurrence may be detected more accurately with contrast-enhanced colour Doppler imaging.

METHODS

Fifty-eight women with suspected local breast cancer recurrence were evaluated prospectively by means of conventional and contrast-enhanced colour Doppler imaging before surgical biopsy.

RESULTS

Sensitivity for the detection of breast cancer recurrence using contrast enhancement was 94 per cent (specificity 67 per cent). Contrast enhancement significantly increased overall diagnostic accuracy, from 80 to 90 per cent (P < 0. 04).

CONCLUSION

Contrast-enhanced colour Doppler imaging is a highly accurate method for detecting local breast cancer recurrence. Its adoption may substantially reduce biopsy rates.