Role of SNAP-23 in trafficking of H+-ATPase in cultured inner medullary collecting duct cells

The trafficking of H+-ATPase vesicles to the apical membrane of inner medullary collecting duct (IMCD) cells utilizes a mechanism similar to that described in neurosecretory cells involving soluble N-ethylmaleimide-sensitive factor attachment protein target receptor (SNARE) proteins. Regulated exocytosis of these vesicles is associated with the formation of SNARE complexes. Clostridial neurotoxins that specifically cleave the target (t-) SNARE, syntaxin-1, or the vesicle SNARE, vesicle-associated membrane protein-2, reduce SNARE complex formation, H+-ATPase translocation to the apical membrane, and inhibit H+ secretion. The purpose of these experiments was to characterize the physiological role of a second t-SNARE, soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP)-23, a homologue of the neuronal SNAP-25, in regulated exocytosis of H+-ATPase vesicles. Our experiments document that 25-50 nM botulinum toxin (Bot) A or E cleaves rat SNAP-23 and thereby reduces immunodetectable and (35)S-labeled SNAP-23 by >60% within 60 min. Addition of 25 nM BotE to IMCD homogenates reduces the amount of the 20 S-like SNARE complex that can be immunoprecipitated from the homogenate. Treatment of intact IMCD monolayers with BotE reduces the amount of H+-ATPase translocated to the apical membrane by 52 +/- 2% of control and reduces the rate of H+ secretion by 77 +/- 3% after acute cell acidification. We conclude that SNAP-23 is a substrate for botulinum toxin proteolysis and has a critical role in the regulation of H+-ATPase exocytosis and H+ secretion in these renal epithelial cells.

Intrapericardial teratoma masquerading as pyopericardium

A 10-year-old boy was admitted with cardiac tamponade. Initial pericardiocentasis yielded pus. A subxiphoid tube-pericardiostomy was done and thick, purulent material was drained out. Subsequently, pericardiectomy was undertaken as features of pericardial constriction persisted. At surgery, however, an intrapericardial mass was discovered. Successful excision was performed and the patient made an uneventful recovery. Histopathology of the mass revealed features of an intrapericardial teratoma. Rarity of the lesion, and a hitherto unreported mode of presentation make this case worthy of documentation.

A unified treatment regimen for new cases of tuberculosis in resource-poor countries: a study in a rural district in Malawi

An oral ambulatory unified treatment regimen was introduced in Ntcheu District, Malawi, between April 1996 and June 1997 for all new patients (600) with tuberculosis (TB). There was no change in the case finding pattern compared with the previous 5 years; 65% of new smear-positive pulmonary tuberculosis (PTB) patients completed treatment, not significantly different compared with the previous 3 years. Treatment completion was significantly lower in patients with smear-negative PTB and extra-pulmonary tuberculosis, due mainly to high mortality rates (40% and 41% respectively). In a rural district with high human immunodeficiency virus sero-prevalence rates in TB patients, case finding and end of treatment outcome of the oral unified regimen were comparable to those of previous regimens.

Dentine caries: take it or leave it?

In modern dentistry the primary aim when excavating carious dentine is to eradicate only the highly infected, irreversibly demineralised and denatured biomass in order to allow effective restoration of the cavity, restoration of the surface anatomy of the tooth and to prevent disease progression. However, the boundary between this superficial zone of dentine requiring excavation and the deeper, affected but repairable tissue is not always obvious either in the clinic or in the research laboratory. The inherent subjectivity in detecting this excavation boundary can result in clinically significant differences in the quality and quantity of dentine removed by different operators and makes the in vitro comparison of newer excavation techniques more difficult. This article discusses the rationale behind carious dentine excavation and the criteria available to the dentist, both clinical and laboratory, to help identify the dentine requiring removal.

Echocardiographic assessment of the right ventricular response to exercise

Although exercise echocardiography has been widely used among adult patients, its application in the pediatric population has not been well explored. A few studies have examined the response of the pediatric left ventricle (LV) to exercise. However, although many congenital heart defects result in abnormalities of right ventricle (RV) anatomy and function, little is known about the RV's response to exercise. The purpose of this study was to assess the effect of exercise on RV dimensions and function and to compare the RV's response to that of the LV. Twenty-nine consecutive pediatric subjects (age 12.1 +/- 3.2 years) with structurally normal hearts, who were referred for exercise stress testing, were studied echocardiographically prior to and within 2 minutes following peak exercise. Adequate studies were obtained in 28 of the 29 patients. RV dimensions and area during the first 2 minutes following the termination of exercise were slightly smaller than those observed prior to exercise. However, the decline in RV area at end systole was proportionally greater than the decline in RV area at end diastole. Consequently, the RV fractional area change following exercise exceeded the preexercise value. The response of the LV to exercise was qualitatively similar to that observed for the RV. This study demonstrates that echocardiographic measurement of RV size and function immediately after exercise is feasible. Data from this study can be used as normal reference standards against which data from patients with congenital heart defects may be compared.

Proper timing of blood cardioplegia in infant lambs: superiority of a multiple-dose regimen

BACKGROUND

In the pediatric and infant age groups, it is unclear whether repeated infusions of blood cardioplegia solution during ischemic arrest are beneficial or detrimental when compared with a single-dose regimen.

METHODS

Twenty lambs (aged 6 to 7 weeks) were placed on cardiopulmonary bypass. A miniature glass-tip electrode measured myocardial pH and hydrogen ion concentration, [H+], in the anterior wall. The aorta was clamped for 2 hours. Group S (n = 10) received a single dose of blood cardioplegia solution. Group M (n = 10) received multiple doses of blood cardioplegia solution at 20-minute intervals.

RESULTS

The amount of [H+] generated during the cross-clamp period was greater in group S than in group M (39.2 +/- 10.1 nmol/L versus 0.4 +/- 1.4 nmol/L, p < 0.008). The percent increase in the time constant, tau, an index of diastolic relaxation, was more prolonged after cardiopulmonary bypass in group S when compared with group M (51.4% +/- 2.8% versus 6.4% +/- 3.0%, p < 0.0001). Similarly, the percent decrease in end systolic elastance, a measure of systolic contractility, was greater in group S after cardiopulmonary bypass when compared with group M (29.5% +/- 1.4% versus 7.3% +/- 1.3%, p < 0.0001).

CONCLUSIONS

In this infant lamb model, multiple doses of blood cardioplegia solution provided superior metabolic preservation and hemodynamic support after 2 hours of aortic clamping when compared with a single-dose regimen.

Application of seminal germ cell morphology and semen biochemistry in the diagnosis and management of azoospermic subjects

AIM

To evaluate whether the study of seminal germ cell morphology (SGCM) and semen biochemistry could be fruitfully utilized for the diagnosis and management of azoospermic subjects.

METHODS

In the semen, mature and immature germ cells are contributed by the testes, 70% of glycerylphosphoryl choline (GPC) by the epididymis, fructose mostly or solely by the seminal vesicles and acid phosphatase [corrected] (ACP) by the prostate. In 16 normal volunteers, 12 vasectomized subjects and 186 azoospermic subjects, these parameters have been studied and the data have been analyzed.

RESULTS

Both mature and immature germ cells are absent in the semen of vasectomized subjects as well as in obstructive azoospermia; GPC level is also significantly decreased in both these groups. In cases with non-obstructive azoospermia immature germ cells are present and seminal GPC, ACP and fructose levels are normal. The diagnosis of obstructive and non-obstructive azoospermia based on these parameters correlated well with "correct" testicular biopsy findings. In some cases of azoospermia due to hypospermatogenesis or spermatogenic developmental arrest, the SGCM studies were very helpful in objectively monitoring the response of the germinal tissue to specific treatments.

CONCLUSION

SGCM and semen biochemical parameters are very valuable non-invasive markers for differentiating obstructive from non-obstructive azoospermia. The SGCM findings serve as a dependable non-invasive testicular marker with high predictive value.

Alveolar rhabdomyosarcoma of the parotid gland

Alveolar rhabdomyosarcoma of the parotid gland is a rare condition. The treatment should involve an aggressive multi-modality approach incorporating surgical removal of the tumour, radiotherapy, and multi-agent chemotherapy. The presentation of this condition along with the most appropriate line of treatment is discussed.

Recognition and stabilization of a unique CPRI--structural motif in cucurbitaceae family trypsin inhibitor peptides: molecular dynamics based homology modeling using the X-ray structure of MCTI-II

The high resolution crystallographic structure of MCTI-II complexed with beta trypsin (PDB entry 1MCT) was used to model the corresponding structures of the six inhibitor peptides belonging to Cucurbitaceae family (MCTI-I, LA-1, LA-2, CMTI-I, CMTI-III, CMTI-IV). Two model inhibitors, LA-1 and LA-2 were refined by molecular dynamics to estimate the average solution structure. The difference accessible surface area (DASA) study of the inhibitors with and without trypsin revealed the Arginine and other residues of the inhibitors which bind to trypsin. The hydration dynamics study of LA1 and LA2 also confirm the suitability of water molecules at the active Arg site. Moreover, the presence of a unique 3D-structural motif comprises with the four CPRI residues from the amino terminal is thought to be conserved in all the six studied inhibitors, which seems essential for the directional fixation for proper complexation of the Arg (5) residue towards the trypsin S1-binding pocket. The role of the disulphide linkage in the geometrical stabilization of CPRI (Cysteine, Proline, Arginine, Isoleucine) motif has also been envisaged from the comparative higher intra molecular Cys (3) -Cys (20) disulphide dihedral energies.

On the phase-space dynamics of systems of spiking neurons. I: model and experiments

We investigate the phase-space dynamics of a general model of local systems of biological neurons in order to deduce the salient dynamical characteristics of such systems. In this article, we present a detailed exposition of an abstract dynamical system that models systems of biological neurons. The abstract system is based on a limited set of realistic assumptions and thus accommodates a wide range of neuronal models. Simulation results are presented for several instantiations of the abstract system, each modeling a typical neocortical column to a different degree of accuracy. The results demonstrate that the dynamics of the systems are generally consistent with that observed in neurophysiological experiments. They reveal that the qualitative behavior of the class of systems can be classified into three distinct categories: quiescence, intense periodic activity resembling a state of seizure, and sustained chaos over the range of intrinsic activity typically associated with normal operational conditions in the neocortex. We discuss basic ramifications of this result with regard to the computational nature of neocortical neuronal systems.

Wegener's granulomatosis: diagnostic dilemma

Wegener's granulomatosis is a systemic disease characterized by a granulomatous lesion that can affect any organ throughout the body. This case-report illustrates the problem posed by a patient presenting with bilateral serous otitis media with marked sensorineural hearing loss, facial nerve paralysis and an atypical serological picture. The importance of early diagnosis and the protocol for the management of a patient with an uncertain diagnosis is discussed. Due to atypical presentations, only a high index of suspicion will ensure an early diagnosis.

HEIGHT AND WEIGHT PATTERNS AS INDICATORS OF GROWTH AMONG SCHOOL CHILDREN IN AN AIR FORCE STATION : A CROSS-SECTIONAL STUDY

A cross sectional study of school children between 6-17 years of age was carried out in an Air Force Station to determine their growth patterns as indicated by weight and height with a view to detect gender bias, if any, and compare the findings with those of affluent Indian children and National Centre for Health Statistics (NCHS), USA, standards. A total of 763 boys and 605 girls were examined. There was no gender bias in growth. Though the children compared almost favourably, with affluent Indian children, particularly in respect to stature, they were lagging far behind the NCHS standard. Goal for achieving the NCHS standards in the long run has been discussed.

On the phase-space dynamics of systems of spiking neurons. II: formal analysis

We begin with a brief review of the abstract dynamical system that models systems of biological neurons, introduced in the original article. We then analyze the dynamics of the system. Formal analysis of local properties of flows reveals contraction, expansion, and folding in different sections of the phase-space. The criterion for the system, set up to model a typical neocortical column, to be sensitive to initial conditions is identified. Based on physiological parameters, we then deduce that periodic orbits in the region of the phase-space corresponding to normal operational conditions in the neocortex are almost surely (with probability 1) unstable, those in the region corresponding to seizure-like conditions are almost surely stable, and trajectories in the region corresponding to normal operational conditions are almost surely sensitive to initial conditions. Next, we present a procedure that isolates all basic sets, complex sets, and attractors incrementally. Based on the two sets of results, we conclude that chaotic attractors that are potentially anisotropic play a central role in the dynamics of such systems. Finally, we examine the impact of this result on the computational nature of neocortical neuronal systems.

Effect of alpha-oligosaccharide phenotype of Neisseria gonorrhoeae strain MS11 on invasion of Chang conjunctival, HEC-1-B endometrial, and ME-180 cervical cells

The genes encoding the glycosyltransferases responsible for the addition of the five sugars in the alpha-oligosaccharide (alpha-OS) moiety of lipooligosaccharide (LOS) have been identified. Disruption of these glycosyltransferase genes singly or in combination results in corresponding truncations in LOS. In the present work we show that sequential deletion of the terminal four sugar residues of gonococcal alpha-OS had no discernible effect on the invasion of human conjunctival, endometrial, and cervical cell lines. However, deletion of the proximal glucose, which resulted in the complete deletion of alpha-OS, significantly impaired invasion of the gonococci into all three cell lines. The effect of deleting alpha-OS on invasion was independent of and additive to the known invasion-promoting factor OpaA. These data suggest that the proximal glucose residue of the alpha-OS chain of LOS is required for efficient invasion of gonococci into host mucosa.

Regioselective enzymatic aminoacylation of lobucavir to give an intermediate for lobucavir prodrug

Synthesis of lobucavir prodrug, L-valine, [(1S,2R,3R)-3-(2-amino-1,6-dihydro-6-oxo-9H-purin-9-yl)-2-(hydroxymethyl) cyclobutyl]methyl ester monohydrochloride (BMS 233866), requires regioselective coupling of one of the two hydroxyl groups of lobucavir (BMS 180194) with valine. Either hydroxyl group of lobucavir could be selectively aminoacylated with valine by using enzymatic reactions. N-[(Phenylmethoxy)carbonyl]-L-valine, [(1R,2R,4S)-2-(2-amino-6-oxo-1H-purin-9-yl)-4-(hydroxymethyl)cyclobutyl]methyl ester (3, 82.5% yield), was obtained by selective hydrolysis of N,N'-bis[(phenylmethoxy)carbonyl]bis[L-valine], O,O'-[(1S,2R,3R)-3-(2-amino-6-oxo-1H-purin-9-yl)cyclobuta-1,2-diyl]methyl ester (1) with lipase M, and L-valine, [(1R,2R,4S)-2-(2-amino-1,6-dihydro-6-oxo-9H-purin-9-yl)-4-(hydroxymethyl)cyclobutyl]methyl ester monohydrochloride (4, 87% yield) was obtained by hydrolysis of bis[L-valine], O,O'-[(1S,2R,3R)-3-(2-amino-6-oxo-1H-purin-9-yl)cyclobuta-1,2-diyl]methyl ester, dihydrochloride (2), with lipase from Candida cylindracea. The final intermediate for lobucavir prodrug, N-[(phenylmethoxy)carbonyl]-L-valine, [(1S,2R,4R)-3-(2-amino-6-oxo-1H-purin-9-yl)-2-(hydroxymethyl)cyclobutyl]methyl ester (5), could be obtained by transesterification of lobucavir using ChiroCLEC BL (61% yield), or more selectively by using immobilized lipase from Pseudomonas cepacia (84% yield).

Local perceptions of tuberculosis in a rural district in Malawi

SETTING

Ntcheu district, Malawi.

OBJECTIVE

To determine 1) the number of patients treated by traditional healers, 2) the type of diseases managed by them, 3) the perceived causes of these disease, and 4) how both patients and healers looked at tuberculosis (TB).

DESIGN

In-depth interviews and structured questionnaires with traditional healers, and focus group discussions with TB patients and their guardians.

RESULTS

Traditional healers recognized four main causes of disease, related to why the patient is sick rather than what the patient is suffering from. Two hundred and seventy-six traditional healers saw approximately 4600 patients a week, managing a variety of diseases, mainly of a chronic nature. Twenty-four per cent of patients seen by traditional healers had a cough, including patients with TB. Traditional healers believe they can cure TB, and have therefore been briefed on the infectious form of TB (smear-positive cases). The possibility of including traditional healers in early diagnosis has been explored.

CONCLUSION

There is a need to address local beliefs in health education and possibly find ways of involving healers in supervision of treatment.

Identification of a cysteine residue in the active site of nitroalkane oxidase by modification with N-ethylmaleimide

The flavoprotein nitroalkane oxidase catalyzes the oxidative denitrification of primary or secondary nitroalkanes to the corresponding aldehydes or ketones with production of hydrogen peroxide and nitrite. The enzyme is irreversibly inactivated by treatment with N-ethylmaleimide at pH 7. The inactivation is time-dependent and shows first-order kinetics for three half-lives. The second-order rate constant for inactivation is 3.4 +/- 0.06 m(-)(1) min(-)(1). The competitive inhibitor valerate protects the enzyme from inactivation, indicating an active site-directed modification. Comparison of tryptic maps of enzyme treated with N-[ethyl-1-(14)C]maleimide in the absence and presence of valerate shows a single radioactive peptide differentially labeled in the unprotected enzyme. The sequence of this peptide was determined to be LLNEVMCYPLFDGGNIGLR using Edman degradation and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The cysteine residue was identified as the site of alkylation by ion trap mass spectrometry.

Autofluorescence and mineral content of carious dentine: scanning optical and backscattered electron microscopic studies

The aim of this study was to investigate the extent of natural intrinsic fluorescence in carious human dentine and any correspondence of such autofluorescence (AF) to the mineral distribution within the lesion. Two investigative techniques were used, both employing the same sample set and fields in diamond-polished block surfaces of polymethylmethacrylate-embedded carious teeth. AF at emission wavelengths >515 nm, excited by 488-nm laser light, was assessed using a confocal laser scanning optical microscope (CLSM), the recordings made under standard operating conditions. The relative mineral content was assessed using digital backscattered scanning electron microscopy (20 kV BSE-SEM). The AF intensity correlated with the level of demineralisation as seen by BSE, but the depth of the lesion as seen by CLSM was significantly greater implying that the AF is not directly related to the mineral component.

The impact of antidepressants on sleep and anxiety: a comparative study of fluoxetine and dothiepin using the Leeds Sleep Evaluation Questionnaire

Fluoxetine (20 mg) was compared to dothiepin (150 mg) in a multicentre, prospective, double blind, randomised clinical trial involving 125 patients with major depression treated for an initial phase of 6 weeks and then followed up for a further 6 months. There was no difference in the efficacy of the two drugs based on the results of established rating scales (MADRS, HAM-D, BPRS). The impact of both drugs on sleep measured using the Leeds Sleep Evaluation Questionnaire showed no significant differences between treatments, however drowsiness and disturbed sleep were reported more frequently as side effects with dothiepin. Symptoms of anxiety responded equally well to both treatments. The short term and long term tolerability of dothiepin was inferior to that of fluoxetine. The place of dothiepin in treatment should be reassessed in the light of its anticholinergic adverse event profile, particularly in the elderly. Copyright 2000 John Wiley & Sons, Ltd.