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J Hypolite

Publications and source records attributed to J Hypolite.

17 recordsLinked to original sources
PubMed2005

[HIV seroprevalence among tuberculosis patients in Nkembo Hospital, Libreville, Gabon. Short note].

There are nearly 31,000 HIV infected patients in Gabon. In Libreville, the capital, the prevalence is estimated at 7.7%. About 2627 tuberculosis patients, all types included, have been notified in 2001 to the World Health Organization of which 43% of smear positive new cases. The co-infection HIV-TB worsens the overall prognosis of our patients. The objective of our study is to determine the HIV seroprevalence among our tuberculosis patients. It is a cross-sectional study conducted between June 25th and August 31th 2001. All patients are new or relapse tuberculosis cases. There is no difference between the types of tuberculosis. The diagnosis was clinical, radiological and based on smear AFB sputum (according to the Ziehl Neelsen method). The patients agreed orally for HIV testing. We made two tests: a rapid one followed by Elisa if positive. 358 patients were examined among them 141 women and 217 men. The M/F sex ratio was 1.53 and the average age 32 years. Proportion of new patients reached 61%. Ninety seven per cent of patients suffered from a pulmonary tuberculosis, 58% smear positive and 26% were HIV-1 positive. According to this status, no statistical difference was notified towards sex, types of disease or patients and the smear sputum results.

Adult↗
PubMed1998

Expression of myosin isoforms in smooth muscle cells in the corpus cavernosum penis.

Corpus cavernosum smooth muscle (CCSM) in the penis is unique in that it exhibits a high resting tone and, on stimulation, the muscle cells relax, allowing cavernous spaces to fill with blood, which results in an erection (tumescence). During detumescence, the muscle cells contract and return to the state of high resting tone. This study was undertaken to determine whether CCSM with these unique properties contains myosin isoforms typical of aorta or bladder smooth muscles, muscles that exhibit tonic and phasic characteristics, respectively. RT-PCR revealed that normal CCSM contains an SM2/SM1 mRNA ratio of 1.2:1 (similar to the rabbit aorta). Approximately 31% of the myosin heavy chain transcripts possess a 21-nt insert (predominant in bladder smooth muscle but not expressed in aorta) that encodes the seven-amino acid insert near the NH2-terminal ATP binding region in the head portion of the myosin molecule found in SMB, with the remaining mRNA being noninserted (SMA). Quantitative competitive RT-PCR revealed that the CCSM possesses approximately 4.5-fold less SMB than the bladder smooth muscle. Western blot analysis using an antibody specific for the seven-amino acid insert reveals that both SM1 and SM2 in the CCSM contain the seven-amino acid insert. Furthermore, SMB containing the seven-amino acid insert was localized in the CCSM by immunofluorescence microscopy using this highly specific antibody. The analysis of the expression of LC17 isoforms a and b in the CCSM revealed that it is similar to that of bladder smooth muscle. Thus the CCSM possesses an overall myosin isoform composition intermediate between aorta and bladder smooth muscles, which generally express tonic- and phasiclike characteristics, respectively. Two-dimensional gel electrophoresis showed a relatively low level (approximately 10%) of Ca2+-dependent light-chain (LC20) phosphorylation at the basal tone, which reaches approximately 23% in response to maximal stimulation. The presence of noninserted and inserted myosin isoforms with low and high levels of actin-activated ATPase activities, respectively, in the CCSM may contribute to the ability of the CCSM to remain in a state of high resting tone and to relax rapidly for normal penile function.

Animals↗
PubMed1997

Acidosis impairs rabbit trabecular smooth muscle contractility.

PURPOSE: The aim of our study was to define the effects of acidosis on the contractility of trabecular smooth muscle. METHODS: Rabbit corpus cavernosal strips were mounted in organ chambers to measure isometric tension. Additionally, intracellular free Ca2+ concentration ([Ca2+]i) and tension were measured simultaneously utilising the intracellular fluorescent dye, FURA-2, and isometric tension recordings. RESULTS: Contraction of corpus cavernosum smooth muscle following transmural electrical stimulation (TES) of constrictor nerves or exposure to norepinephrine was depressed under acidic (pH 6.9) vs. control (pH 7.4) conditions. Twenty mM K(+)-induced contractions were also inhibited by acidosis, however 40, 80, and 120 mM K+ contractions were unaffected. Relaxation responses to acetylcholine and electrical stimulation, in phenylephrine contracted tissues, were unaffected by acidosis. Tissues contracted with 20 mM K+ under control conditions, relaxed approximately 50% when exposed to an acidic environment. This relaxation was blocked by exposing the tissue to 80 mM K+. Acidic conditions inhibited basal tone and [Ca2+]i as well as normal increases in both intracellular free Ca2+ and tension upon exposure to 20 mM K+, while 80 mM K(+)-induced increases in Ca2+ and tension were comparable under both neutral and acidic conditions. CONCLUSION: Acidosis impairs trabecular smooth muscle contractility. This alteration is probably secondary to the interference of [H+] with the intra and extracellular mechanisms that regulate homeostasis of [Ca2+]i. Since acidosis is an early complication of ischemic priapism, we propose that the reduced contractility of trabecular smooth muscle may be a significant factor in the perpetuation of the ischemic state.

Acetylcholine↗
PubMed1996

Altered contractility of rabbit penile corpus cavernosum smooth muscle by hypoxia.

PURPOSE: To investigate the effects of severe hypoxia on trabecular smooth muscle contractility. MATERIALS AND METHODS: Strips of rabbit corpus cavernosum were mounted in organ chambers to measure isometric tension. In some experiments intracellular free Ca2+ concentration and tension were measured by the intracellular fluorescent dye FURA-2 and isometric tension recording simultaneously. RESULTS: Contractions elicited by norepinephrine, endothelin-1 or potassium were attenuated under hypoxic conditions (pO2 approximately 10 mm. Hg). Strips contracted with 20 mM. K+ under normoxic conditions and then exposed to hypoxia consistently lost the potassium-induced tone. The hypoxia-induced relaxation was not affected by the removal of the endothelium, by treatment with the cyclooxygenase blocker, indomethacin, or with the guanylate cyclase blocker, methylene blue. The potassium channel opener, cromakalim, and adenosine relaxed potassium contracted strips; however, the potassium channel blockers glibenclamide, apamin, barium chloride and charybdotoxin or the adenosine receptor antagonist 8-(p-sulfonyl)theophylline were unable to prevent hypoxia-induced relaxation. Tetraethylammonium, a potassium channel blocker, and the depolarizing agents ouabain and high potassium (80 mM.), partially prevented hypoxia-induced relaxation. The calcium ionophore, ionomycin, had no effect on hypoxia-induced relaxations. Hypoxia, within 2 to 6 minutes, caused a large accumulation in intracellular calcium, concomitant with a loss of trabecular smooth muscle tone. Both these effects could be reproduced by inhibiting oxidative phosphorylation with 2,4,dinitrophenol. Reoxygenation resulted in an immediate recovery of both tone and intracellular calcium levels. Tissues under hypoxic conditions for 30 minutes had a 24% and 67% decrease in the ATP/ADP ratio and in creatine phosphate concentrations, respectively. CONCLUSION: Hypoxia causes a simultaneous increase in intracellular calcium and relaxation which, we propose, is the consequence of inhibition of oxidative phosphorylation with loss of high energy phosphates, necessary for the homeostasis of Ca2+ and the contractile mechanism of the cavernosal smooth muscle.

Adenosine Diphosphate↗
PubMed1994

Comparative studies on intracellular calcium and NADH Fluorescence of the rabbit corpus cavernosum.

Erectile function (erection and detumescence) involves the complex interaction of direct neuronal stimulation of corporal smooth muscle, neurohumoral release of specific endothelial contractile and relaxant factors, and secondary modulation by a variety of putative neuropeptides and vasoactive modulators. Using surface spectrofluorometry, we have correlated spontaneous contractile activity and the contractile response to field and pharmacological agents with intracellular calcium and NADH metabolism. The results demonstrate that the corpus cavernosal tissue has very unusual properties. Spontaneous contractile activity is correlated with a phasic increase in intracellular calcium. However, spontaneous contractile activity is most often correlated with a bi-phasic effect on the ratio of NADH/NAD. At the start of the spontaneous contraction, there is a sharp phasic increase in NADH/NAD; peak contractile force occurs simultaneous with a phasic decrease in this ratio showing that at peak force generation, there is a decrease in the level of intracellular energy. Phenylephrine stimulation results in an increase in intracellular calcium in proportion to the increase in tension; however, phenylephrine stimulation at low concentrations results in a net increase in the NADH/NAD ratio whereas high concentrations of phenylephrine result in a net decrease in the NADH/NAD ratio. In general, field stimulation results in a decrease in tension at low frequencies, a biphasic response at midfrequencies, and a contraction at high frequencies. These contractile responses are directly directly related to alterations in the intracellular concentration of calcium. That is, a decrease in tension is preceded by a decrease in intracellular calcium while an increase in tension is preceded by an increase in intracellular free calcium. Field stimulation results in a rapid and phasic alteration in the NADH/NAD ratio; however, the NADH/NAD response can be either an increase, decrease, or biphasic response. There does not appear to be a consistent relationship between the contractile/relaxant response to field stimulation and altered NADH/NAD ratio. Finally, ATP, bethanechol, and nitroprusside induce a decrease in the basal tension of the corpus cavernosal strips which corresponds with a decrease in the NADH/NAD ratio. However, whereas nitroprusside relaxation is correlated with a decreased intracellular calcium level, both ATP and bethanechol stimulate an increase in intracellular free calcium. These studies indicate that the response of the corpus cavernosal tissue to both field stimulation and pharmacological agents is complex and may involve both direct and indirect actions of a variety of cellular mediators on the corporal smooth muscle.

Animals↗
PubMed1994

Anoxia and corporal smooth muscle dysfunction: a model for ischemic priapism.

The hemodynamics of penile flaccidity, erection and detumescence requires corporal smooth muscle to function across a wide variation in pO2. The present study describes the effect of anoxia on corporal smooth muscle response to field stimulation and pharmacologic agonists and antagonists of erection. The response of isolated strips of rabbit corpus cavernosal tissue to field stimulation, phenylephrine, bethanechol, ATP and KCL was determined under oxygenated and anoxic conditions. The results can be summarized as follows: 1) Anoxia eliminated spontaneous contractile activity and reduced basal tissue tension to a minimum. 2) Neither field stimulation nor pharmacological agents (ATP, bethanechol, isoproterenol) could relax basal tension below that induced by anoxia alone. 3) Under anoxic conditions alpha-adrenergic agonists produced poorly sustained phasic contractile responses; anoxia eliminated tonic contractile responses to phenylephrine. 4) In normoxic conditions field stimulation of smooth muscle precontracted with phenylephrine produced frequency-dependent graded relaxations; under anoxic conditions field stimulation yielded contractile responses at all frequencies. Our data suggest that corporal smooth muscle tone, spontaneous contractile activity, the contractile response to alpha-agonists and field stimulated relaxation depend on the state of corporal oxygenation. The inability of alpha-stimulation to induce a tonic contraction of corporal smooth muscle under anoxia in vitro parallels the failure of penile injection of alpha-adrenergic agonists to relax ischemic priapism.

Animals↗
PubMed1992

Correlations of purinergic, cholinergic and adrenergic functions in rabbit corporal cavernosal tissue.

Erection involves cholinergic, adrenergic as well as non-cholinergic non-adrenergic nerves. Endothelial-derived relaxation factor plays an important role in mediating smooth muscle relaxation, which is crucial in initiating and maintaining erection. We previously showed that adenosine 5'-triphosphate (ATP) can induce significant relaxation in rabbit corporal cavernosal tissue. The present study presents effects of different neurotransmitters and the role of endothelium in controlling the contractile/relaxant status of rabbit cavernosal tissue. These studies utilized isolated tissue strips prepared from the corpus cavernosum of sexually mature male New Zealand white rabbits. The results can be summarized as follows: (1) field stimulation caused relaxations with rebound contractions in most strips; (2) bethanechol (250 microM), isoproterenol (20 microM) and ATP (1 mM) all induced relaxations, though the relaxation induced by bethanechol was poorly sustained; (3) removal of the endothelium by rubbing decreased the relaxation to field stimulation and virtually eliminated the relaxation induced by bethanechol, but had no effect on the relaxation responses to isoproterenol and ATP; (4) methoxamine (200 microM) stimulated a sustained contraction of corporal cavernosal tissue, an effect unaltered by rubbing the strips; (5) low dose epinephrine induced relaxation, whereas higher concentrations contracted the tissue, and (6) beta-adrenergic inhibition with propranolol (20 microM) was significantly more effective than mascarinic blockade with atropine (20 microM) in eliminating relaxation caused by field stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Comparison of the contractile and metabolic effects of muscarinic stimulation with those of KCl.

Urinary bladder emptying is mediated primarily by a coordinated contraction of the bladder body in response to parasympathetic stimulation and muscarinic receptor activation. In previous studies we presented evidence that the contractile response to bethanechol stimulation could be dissociated from the metabolic response through the use of diltiazem (calcium channel blockade). The conclusion from these studies was that muscarinic stimulation resulted in a significant increase in metabolic activity which was not directly associated with contraction. KCl stimulates contraction in isolated strips by directly depolarizing the membrane rather than from binding to specific membrane receptors. The current study directly compares the metabolic and contractile activity of bethanechol (muscarinic stimulation) with KCl (direct membrane depolarization). Isolated strips of rabbit urinary bladder body were monitored in vitro for changes in intracellular-free calcium, NADH/NAD ratio, and contraction. Intracellular-free calcium was monitored by preincubation of isolated bladder smooth muscle strips with FURA-2 AM and continuously measuring the fluorescence with an MB2 surface spectrofluorometer using excitation wavelengths of 340 and 380 nm, and an emission wavelength of 510 nm. The NADH/NAD ratio was monitored with the MB2 surface spectrophotometer using an excitation wavelength of 366 nm and an emission wavelength of 450 nm. Contraction was monitored using a isometric force transducer connected to a Grass model D polygraph. The results can be summarized as follows. (1) Both bethanechol and KCl stimulate a sharp decrease in the NADH/NAD ratio, a rapid increase in intracellular-free calcium, and a slower increase in contractile force.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1991

Developmental aspects of bladder contractile function: sensitivity to extracellular calcium.

The urinary bladders of 1-day and 1-week-old rabbits generate higher intravesical pressures in response to bethanechol and field stimulation than bladders isolated from mature 8-week-old rabbits. Yet the density of cholinergic receptors in the rabbit bladder does not change with maturation (1 day to 8 weeks). In an effort to better understand the molecular mechanisms by which newborn rabbit bladders generate greater pressures than the bladders of adult rabbits, we studied the effect of maturation on the relationship between extracellular calcium and contraction. Our results showed quite clearly that (1) at physiologic concentrations of calcium (2.5 mumol/l), isolated bladder strips of 1-day- and 1-week-old rabbits contracted in response to bethanechol to 98% of their maximal tension as opposed to 68% for their 8-week-old counterparts, (2) the ED50 (for calcium) for the 1-day and 1-week bladders was 0.4 mmol/l whereas the ED50 for the adult bladder strips was 2.2 mmol/l, and (3) the neonatal bladders demonstrated a much greater sensitivity to diltiazem than the adult bladders. The contractile response to calcium of the neonatal bladders was significantly inhibited by 1 mumol/l diltiazem whereas the 8-week-old bladders showed no inhibition at this concentration. In a second series of experiments, the effect of extracellular calcium on concentration was correlated with the intracellular concentration of free calcium using the calcium fluoride FURA-2 and surface spectrofluorometry. These studies confirmed that the increased contractile response of the neonatal bladder strips to calcium or cholinergic agonists was associated with an increase in the maximal intracellular free calcium concentration.

Animals↗
PubMed1989

Effects of muscarinic stimulation on intracellular calcium in the rabbit bladder: comparison with metabolic response.

Urinary bladder emptying is mediated primarily by a co-ordinated contraction of the bladder body in response to parasympathetic stimulation and muscarinic receptor activation. In a previous study using surface spectrophotometry to monitor the nicotinamide adenine dinucleotide (oxidized form)/nicotinamide adenine dinucleotide (reduced form) (NADH/NAD) ratio, we demonstrated that muscarinic stimulation results in a rapid decrease in this ratio which precedes the contractile response, and that the ED50 for the NADH response is significantly lower than the ED50 for contraction. The current study was designed to correlate changes in intracellular free calcium using FURA-2 fluorescence with both the contractile and metabolic response to muscarinic stimulation. Isolated strips of urinary bladder body were monitored in vitro for changes in intracellular free calcium, NADH/NAD ratio, and contraction. Intracellular free calcium was monitored by preincubation with FURA-2 AM and continuously measuring the fluorescence with an MB2 surface spectrofluorometer using excitation wavelengths of 340 and 380 nm, and an emission wavelength of 510 nm. The NADH/NAD ratio was monitored with the MB2 surface spectrophotometer using an excitation wavelength of 366 nm and an emission wavelength of 450 nm. Contraction was monitored using an isometric force transducer connected to a Grass model D polygraph. The results can be summarized as follows: (1) Bethanechol stimulates a sharp decrease in the NADH/NAD ratio, a rapid increase in intracellular free calcium, and a slower increase in contractile force. (2) The ED50 for NADH fluorescence was significantly less than the ED50 for either contraction or calcium fluorescence which were equal to each other.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Comparative study of two computerized semen motility analyzers.

Semen analysis is one of the primary tests carried out to investigate the infertile male. Subjective evaluation of semen is often prone to observer bias and error. To eliminate this, a number of computerized semen analyzers have recently been introduced into the market and we have evaluated two of the more popular models, the Cell Soft Semen Analyzer and the Hamilton Thorn Motility Analyzer (HTM 2000). The Cell Soft identifies sperm on the basis of user defined values for cell size and luminosity whereas the Hamilton Thorn identifies sperm by motility, and then applies the computer-calculated average size and luminosity of all moving objects to non moving sperm cells. Semen samples from 25 normal donors and 25 subfertile patients were analyzed using these two models of computerized semen analyzers, and also by an experienced technician using both the Makler chamber and the hemocytometer. The results obtained from the two automated analyzers were compared with those obtained by subjective evaluation. Variation in sperm count and motility were analyzed according to the sperm density. Four groups, less than 30 million/ml with debris, less than 30 million/ml, 30-50 million/ml, and greater than 50 million/ml were studied. The majority of patients fit into the first two groups. We observed that the HTM 2000 is superior to the Cell Soft in evaluating sperm count within the patient population group. For our donor population with an average sperm count of greater than 85 million/ml both systems provide extremely accurate counts.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMedDate not supplied

Comparative studies on rabbit corpus cavernosal contraction and relaxation. An in vitro study.

Erectile function (erection and detumescence) involves the complex interaction of direct neuronal stimulation of corporal smooth muscle, neurohumoral release of specific endothelial contractile and relaxant factors, and secondary modulation by a variety of putative neuropeptides and vasoactive modulators including nitric oxide. The specific aim of the current study was to determine the relative contribution of nitric oxide, adrenergic, purinergic, and cholinergic stimulation in the relaxant response to field stimulation. The results demonstrate that virtually all of the inhibitory effects of field-stimulated relaxation could be explained by the release of nitric oxide. L-NAME (L-NG-nitro arginine methyl ester, a competitive inhibitor of NO synthase) reduced field-stimulated relaxation by over 95% at all frequencies. Neither atropine nor propranolol (or the combination of the two) had any significant effect on field-stimulated relaxation. L-NAME blocked both field-stimulated relaxation and bethanechol-stimulated relaxation. However, methylene blue (a guanyl cyclase inhibitor) was significantly more potent at blocking bethanechol-stimulated relaxation than field-stimulated relaxation. Neither L-NAME nor methylene blue had any effect on nitroprusside (a direct liberator of NO) nor ATP-stimulated relaxation. Isoproterenol had only a minor inhibitory effect on phenylephrine-contracted tissue. These data suggest that 1) Methylene blue, which inhibits guanyl cyclase, is a relatively poor inhibitor of field-stimulated relaxation. 2) L-NAME is a potent inhibitor of NO synthesis and can in a dose-dependent fashion inhibit over 95% of field-stimulated relaxation. 3) Equipotent relaxation of corporal smooth muscle can be effected through pharmacologic stimulation with ATP (2 mM), nitroprusside (200 microM), and field stimulation (32 Hz).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗