Disruption of the rat mesenteric arterial bed endothelial function by air perfusion

The impact of air perfusion on the endothelial function of the rat mesenteric arterial bed (MAB; perfused with Krebs' bicarbonate plus indomethacin) was compared to that of the NO synthase inhibitor, N(omega)-nitro-L-arginine methyl ester (L-NAME). Air shifted the dose-response curve for the alpha-adrenoceptor agonist, norepinephrine (NE) to the left (ED50%: 2.9+/-0.7 to 0.9+/-0.7 microg, P < 0.05); maximal vasoconstriction did not change. L-NAME produced a similar increase in midrange sensitivity (ED50% 1.4+/-0.7 microg, P < 0.05) and a 20% increase in maximum (152+/-6 to 183+/-7 mmHg, P < 0.05). Electromechanical stimulation with potassium chloride (KCl) was not modified by reserpine. Neither air nor L-NAME modified midrange sensitivity to KCl. L-NAME produced a 17% increase in maximum (91+/-4 to 107+/-5 mmHg, P < 0.05); reserpine abolished the latter effect. Air and L-NAME diminished endothelium-dependent vasodilation elicited by carbachol. Air did not modify endothelium-dependent vasodilation elicited by sodium nitroprusside; this response was potentiated by L-NAME. In summary, air and L-NAME produced similar effects on receptor-dependent activation of the endothelial L-arginine nitric oxide (NO) pathway. Potentiation by L-NAME of the maximal electromechanical response suggests the existence of a tone-dependent NO system. Abolition of the latter response by reserpine suggests that this system is of sympathetic origin.

Small intestinal absorption during endotoxemia in swine

We studied the effects of systemic endotoxemia on small intestinal absorption in an in vivo animal model. Seven adolescent Yorkshire swine underwent creation of 25 cm distal ileal Thiry-Vella fistulae. After 1 week recovery, the fistulae were perfused with a solution of glucose and electrolytes labeled with 14C-PEG, and net absorption of water, Na+, Cl-, and glucose was calculated. Animals were studied under three different conditions: (1) Basal fasting state, (2) immediately after intravenous injection of E. coli lipopolysaccharide (LPS; 250 micrograms/kg), and (3) 24 hours after LPS. Water, Na+, and Cl- absorption was significantly reduced 2 hours after LPS, but recovered to baseline values by the third hour after LPS. Twenty-four hours after LPS water, Na+, and Cl- absorption was significantly decreased below baseline values. Glucose absorption after LPS paralleled that of water and electrolytes, except that the transient early recovery was not observed. Histological studies of the ileum after LPS showed marked epithelial inflammation at 6 hours, villous atrophy at 24 hours, and signs of recovery at 7 days. Intestinal absorption of water, electrolytes, and glucose is adversely affected in the immediate and early periods after an endotoxemic episode, but the histological epithelial injury secondary to endotoxemia is reversible.

Six-month supervised intermittent tuberculosis therapy in Haitian patients with and without HIV infection

We enrolled 427 consecutive patients with tuberculosis diagnosed in Cité Soleil, Haiti in a trial of short-course intermittent therapy. All patients received supervised therapy with isoniazid, rifampin, pyrazinamide, and ethambutol thrice weekly for 8 wk, followed by isoniazid and rifampin thrice weekly for 18 wk. At entry, the 177 human immunodeficiency virus (HIV)-infected patients (42%) were found significantly more likely to have extrapulmonary tuberculosis and negative tuberculin skin tests (p < 0.05). Treatment was well tolerated by both groups of patients, and adherence to the treatment regimen was over 90%. Among patients with pulmonary or intrathoracic tuberculosis, 9% of HIV-seropositive and 1% of HIV-seronegative patients died during therapy (p < 0.001), whereas 81% and 87%, respectively, of those in the two groups were cured. Relapses occurred in 5.4% of HIV-seropositive and 2.8% of HIV-seronegative patients who completed treatment (p = 0.36). Survival after tuberculosis was poorer in HIV-seropositive patients, whose probability of dying was 33% at 18 mo after diagnosis as compared with 3% for HIV-seronegative patients (p < 0.001). HIV-seropositive patients who died had significantly lower median CD4 lymphocyte counts than did HIV-seropositive patients who survived (p < 0.001). Treatment of tuberculosis with short-course, thrice-weekly, supervised therapy in the setting of a developing country is highly efficacious in both HIV-seropositive and -seronegative patients.

Visual function and perinatal focal cerebral infarction

AIMS

To evaluate the visual function of infants with perinatal cerebral infarction in whom the site and size of the lesion has been determined using magnetic resonance imaging (MRI).

METHODS

Twelve infants with cerebral infarction on MRI were studied with a battery of tests specifically designed to evaluate visual function in infancy. This included tests: for visual attention (fixation shifts); of cerebral asymmetry (optokinetic nystagmus, visual fields); for assessment of acuity (forced choice preferential looking); and neurophysiological measures of vision (phase reversal and orientation reversal visual evoked potential).

RESULTS

A considerable incidence of abnormalities on at least one of the tests for visual function used was observed. The presence or severity of visual abnormalities could not always be predicted by the site and extent of the lesion seen on imaging.

CONCLUSIONS

Early focal lesions affecting the visual pathway can, to some extent, be compensated for by the immature developing brain. These data suggest that all the infants presenting with focal lesions need to be investigated with a detailed assessment of various aspects of vision.

Economic perceptions and expectations of out-of-treatment drug users

The effect on mainstream behavior of current economic conditions and expectations for the future is frequently the subject of public opinion polls. However, economic perceptions may also influence the behaviors of those in "hidden" populations, such as drug users. An Economic Perceptions Index (EPI) was developed and administered to 261 out-of-treatment drug users in Houston, Texas. Results suggest that drug users' general perceptions of the economy are based on their own economic situation, and that there is a relation between a pessimistic view of the economy and drug use. They also suggest that lack of municipal infrastructure may pose more of a barrier to users' seeking employment than job search skills.

A simulation model of the dynamics of HIV transmission in intravenous drug users

The complex dynamics of HIV transmission and subsequent progression to AIDS make the use of traditional mathematical modeling techniques problematic. In a previous paper for this journal, Leslie and Brunham established the utility of a nonmathematical simulation language in modeling HIV transfer under conditions similar to those found among homosexual males. This study considers the application of such an approach in modeling HIV spread among intravenous drug users (IDUs) injecting within a "shooting gallery," a location providing a common needle supply to a large number of users. Modeling HIV transmission in this population involves not only consideration of heterogeneity in partnership selection, but also of the fact that spread of the virus is not directly from person to person, but via injection equipment. The General Purpose Simulation System was used to create a hypothetical cohort of IDUs, drawing from a common needle supply. Following introduction of an index case, the HIV infection rate in this cohort was followed over 5 simulated years. The model was then used to consider the effects of systematic variation in the frequency of injection and needle-cleaning behavior.

Inhaled nitric oxide prevents experimental platelet activating factor-induced shock

OBJECTIVE

To investigate whether inhaled nitric oxide (INO) can prevent platelet activating factor (PAF)-induced pulmonary hypertension and shock.

DESIGN

Randomized controlled animal trial.

SETTING

Laboratory.

SUBJECTS

Yorkshire swine.

INTERVENTIONS

Animals received general anesthesia and invasive hemodynamic monitoring, then PAF only, 2.5 micrograms/kg intravenously over 45 minutes (PAF group, n = 9) or PAF in addition to INO, 20 ppm (PAF-INO group, n = 6).

MAIN OUTCOME

Vascular pressures (mean arterial and mean pulmonary), vascular resistance indexes (systemic and pulmonary), cardiac indexes, and oxygen delivery and oxygen consumption.

RESULTS

Mean arterial pressures, cardiac indexes, and oxygen delivery and consumption were significantly higher in the PAF-INO group. Mean pulmonary arterial pressures and systemic and pulmonary vascular resistance indexes were significantly lower in the PAF-INO group. There were 4 deaths (44%) in the PAF group vs none (0%) in the PAF-INO group (P = 10).

CONCLUSIONS

The use of INO prevents pulmonary hypertension, circulatory failure, and death during PAF-induced shock.

Two infant vision screening programmes: prediction and prevention of strabismus and amblyopia from photo- and videorefractive screening

Two infant vision screening programmes on total populations in the Cambridge Health District have been designed to identify manifest strabismus and strabismogenic and amblyogenic refractive errors at 7-9 months of age. The first, completed, programme used the isotropic photorefractor with cycloplegia together with a standard orthoptic examination. The second, current, programme uses the VRP-1 isotropic videorefractor to identify infants with accommodative lags which are followed up by refraction under cycloplegia. Both programmes show good agreement between infants identified at screening and retinoscopic refractions at follow-up, showing that photo- and videorefraction (with or without cycloplegia) can be effective methods for screening for ametropia in infants and young children. In each programme 5-6% of infants showed abnormal levels of hyperopia (> or = 3.5 D in any meridian), less than 1% showed anisometropia > or = 1.5 D; very few infants (0.25%) showed -3D myopia or greater. Less than 1% showed manifest strabismus. Hyperopic and anisometropic children entered a randomised controlled trial of partial refractive correction. All children identified at screening, alongside appropriate control groups, are extensively followed up to age 4 years. The first programme has found that children who were hyperopic in infancy were 13 times more likely to become strabismic, and 6 times more likely to show measurable acuity deficits by 4 years, compared with controls. Wearing a partial spectacle correction reduced these risk ratios to 4:1 and 2.5:1 respectively. The impaired acuity can be attributed, in part, to meridional amblyopia resulting from persisting astigmatism. Both hyperopic and myopic infants showed refractive changes in the direction of emmetropia between 9 months and 4 years. Wearing a partial spectacle correction did not affect this process of emmetropisation, but does provide the possibility of reducing the incidence of common pre-school vision problems.

A new technique for study of impact of arterial elasticity on left ventricular mass in rats

We investigated possible links between left ventricular mass and central arterial elasticity in the adult spontaneously hypertensive rat (SHR) and in a subgroup of SHR in which blood pressure was normalized by chronic antihypertensive drug treatment; results were compared with those of age-matched normotensive Wistar-Kyoto rats. Two indexes of arterial elasticity, based on the measurement of aortic pressure pulse wave velocity, were used. First, the slope relating carotidofemoral pulse wave velocity to blood pressure in the phenylephrine-infused pithed preparation was used as a pressure-independent index of wall elasticity. Second, to account for hypertension- and treatment-induced aortic remodeling, elastic modulus was determined from the pulse wave velocity recorded when blood pressure reached that measured in awake animals before anesthesia and pithing, together with values for wall thickness and lumen diameter evaluated by histomorphometric analysis after in situ fixation at the same pressure. In control SHR, regression analysis of variance revealed significant correlations between left ventricular mass and both wave velocity/pressure slope and elastic modulus. Chronic antihypertensive treatment normalized all three parameters. In conclusion, this new technique provides experimental evidence of a link between left ventricular mass and central arterial elasticity.

Sustained pulmonary vasodilation after inhaled nitric oxide for hypoxic pulmonary hypertension in swine

It has been shown that pulmonary vasodilation is sustained after discontinuation of inhaled nitric oxide (INO) during moderate hypoxic pulmonary hypertension (HPH) in swine. The present investigations demonstrated how INO dose, hypoxia duration, and endogenous NO production influence this important phenomenon. Fifteen adolescent Yorkshire swine were randomly assigned to three groups (n = 5 each) and underwent the following phasic experimental protocol: (I) Baseline ventilation (FIO2 = .3); (II) Initiating HPH (FIO2 = .16 to .18, PaO2 = 45 to 55 mm Hg); (III) INO at 10 ppm; (IV) Posttreatment observation; (V) INO of 80 ppm; and (VI) Posttreatment observation. Phase II (pretreatment hypoxia) lasted 30 minutes in group A (short hypoxia) and 120 minutes in group B (long hypoxia). N-nitro-L-arginine methyl ester (NAME) was used to inhibit nitric oxide synthase (NOS) throughout the experiment in group C (short hypoxia + NAME). Hemodynamics and blood gases were monitored by systemic and pulmonary artery catheters placed by femoral cutdown. Analysis of variance with post-hoc adjustment was used to compare groups at each phase, and the paired t test was used for comparisons within a group. With respect to baseline mean pulmonary artery pressure (MPAP) and pulmonary vascular resistance (PVR), there were no significant differences among the three groups. MPAP and PVR were significantly higher in group C than in group A during phase II, (MPAP, 76% +/- 8% v 33% +/- 2%; PVR, 197% +/- 19% v 78% +/- 10%; P < .05). There were no significant differences in MPAP or PVR during phases III through VI. When MPAP was expressed as percent dilation, 80 ppm caused significantly more dilation than did 10 ppm in all three groups. Groups A and C had significantly higher sustained pulmonary artery dilation after 80 ppm than after 10 ppm (A, 82% +/- 31% v 17% +/- 11%; C, 68% +/- 10% v 42% +/- 12%; both P < .05), but group B did not (43% +/- 15% v 30% +/- 9%; P = .25). High dose results in stronger vasodilation than low dose during and after INO for moderate HPH of short duration. Long hypoxia blunts this high-dose advantage. Endogenous NO inhibition augments HPH but does not decrease pulmonary vasodilation during or after INO.

Water transport in native and transplanted porcine jejunum

Adequate absorptive function of transplanted small intestine is essential for success of this procedure. This study compared water transport under basal and meal stimulated conditions in the transplanted swine jejunum to native jejunum. Six female adolescent Yorkshire swine were randomized to undergo construction of either a 25-cm native proximal jejunal Thiry-Vella Fistula (TVF), n=3, or a 25-cm proximal jejunal allograft TVF, n=3. Immunosuppression in the transplanted animals was accomplished with intravenous methylprednisolone, azathioprine, and cyclosporin. Jejunal absorption studies, each 4 hr long, were performed utilizing 14C-polyethylene glycol to calculate net water flux. Each animal underwent at least three fasting and three postprandial studies. New water flux was negative, i.e., secretory, in both the native and transplanted proximal swine jejunum. In the basal state, integrated hourly water transport was more secretory in the native bowel vs the transplanted bowel during the 2nd, 3rd, and 4th experimental hr (-4.6 +/- .8 vs -2.1 +/- .7 cc, P = 0.034; -4.4 +/- .7 vs -1.8 +/- .6 cc, P = 0.012; and -4.7 vs 1.3 +/- .5 cc, P < 0.005), respectively. In native jejunum, integrated hourly water transport was less secretory 2 and 3 hr postprandially compared to basal (-1.9 +/- .5 vs -4.4 +/- .7 cc, P = 0.016; and -2.0 +/- .5 vs -4.7 +/- .7 cc, P = 0.021), respectively. This postprandial proabsorptive response did not occur in the transplanted jejunum. Native and transplanted jejunal water flux in the postprandial state did not differ significantly. We conclude that there is higher secretion in native vs transplanted jejunum during fasting. The postprandial proabsorptive response of the proximal porcine jejunum is abolished by transplantation.

Widespread HIV counseling and testing linked to a community-based tuberculosis control program in a high-risk population

The aim of the work reported here was to evaluate community-wide screening for HIV infection that was linked to a tuberculosis control program in a population at high risk for both infections. Between May 1990 and August 1992, adults in Cité Soleil, Haiti, were recruited by community health workers at their homes and in clinics for individual, clinic-based counseling and testing for HIV and tuberculosis. All of the screened subjects were offered post-test HIV counseling. Those with active tuberculosis received treatment, while those with latent tuberculosis and HIV infection were offered an opportunity to participate in a trial of antituberculosis chemoprophylaxis. The 10,611 individuals screened for HIV represented 10.0% of the adult population in Cité Soleil. HIV infection was detected in 1,629 (15.4%) and active tuberculosis in 242 (2.3%). Latent M. tuberculosis infection was found in 4,800 (67.5%) of 7,309 community residents who completed tuberculosis screening, 781 (16.3%) of whom were coinfected with HIV. The high prevalence of HIV infection found in this screened population, as compared to other groups undergoing HIV screening in the same community, suggests that people at high risk for HIV infection selectively sought or accepted tuberculosis clinic screening. Also, many people with active tuberculosis were identified earlier in the course of their disease than they would have been in the absence of a screening program. Overall, the results indicate that community-based screening for HIV infection within a tuberculosis control program can result in effective targeting of screening for both infections.

Party time in Toronto

Friday is PARTY day at Sunnybrook Health Science Centre (SHSC) and Lyndhurst Hospital, Toronto. This may create a confusing image of balloons and frivolity, but the reality is somewhat different. Although the ingredients for a party exist - young people, pizzas and sodas, this party means PARTY - prevent alcohol and risk related trauma in youth.

Zotepine: preclinical tests predict antipsychotic efficacy and an atypical profile

Zotepine, an atypical antipsychotic structurally similar to clozapine, is in Phase III clinical trials in the United States and Europe for the treatment and management of acute and chronic schizophrenia. Zotepine's pharmacological profile has been compared with those of the atypical antipsychotic clozapine, and the typical neuroleptics haloperidol and chlorpromazine in preclinical tests that predict antipsychotic efficacy and extrapyramidal symptoms (EPS). Because zotepine causes potent, long-lasting inhibition of dopaminergic behavioral responses in animals, it may have an efficacious prolonged antipsychotic action in humans. In contrast, it induces little catalepsy, indicating that it should cause minimal motor side effects, such as EPS. Like clozapine but unlike the typical neuroleptics, zotepine's affinities for cloned human D1 and D2 receptors are very similar. Since a stimulation imbalance favoring D1 over D2 receptors has been suggested to induce dyskinesias, zotepine's reduced EPS profile in humans may derive, in part, from balanced inhibition of these receptors.

Aortic stiffness and left ventricular mass in a rat model of isolated systolic hypertension

We tested whether cardiac mass can be related to decreased aortic stiffness in an original rat model of isolated systolic hypertension. Increased aortic stiffness was produced by calcium overload of elastic arteries after vitamin D3 plus nicotine treatment. Half of the animals were chronically treated with the angiotensin-converting enzyme inhibitor perindopril (1 mg/kg per day PO). Rats were pithed, and lower body vascular resistance was measured. Blood pressure was then increased by phenylephrine infusion, and carotidofemoral pulse wave velocity was measured. This value together with those for thoracic aorta internal diameter and medial thickness (determined after in situ fixation and histomorphometry) were used to calculate elastic modulus. Vitamin D3 plus nicotine treatment produced parallel increases in cardiac mass and elastic modulus, with a significant correlation between the two. There was no significant change in resistance. Treatment with perindopril reversed the changes in cardiac mass and elastic modulus but had no effect on resistance after calcium overload of the elastic arteries. In this model of isolated systolic hypertension, we showed that cardiac mass is related to arterial elasticity.

Context effects on misreading and suppression at UAG codons in human cells

The effect of the 3' codon context on the efficiency of nonsense suppression in mammalian tissue culture cells has been tested. Measurements were made following the transfection of cells with a pRSVgal reporter vector that contained the classical Escherichia coli lacZ UAG allele YA559. The position of this mutation was mapped by virtue of its fortuitous creation of a CTAG MaeI restriction enzyme site. Determination of the local DNA sequence revealed a C-->T mutation at codon 600 of the lacZ gene: CAG-->TAG. Site-directed mutagenesis was used to create a series of vectors in which the base 3' to the nonsense codon was either A, C, G, or U. Suppression of the amber-containing reporter was achieved by cotransfection with genes for human tRNA(Ser) or tRNA(Gln) UAG nonsense suppressors and by growth in the translational error-promoting aminoglycoside drug G418. Nonsense suppression was studied in the human cell lines 293 and MRC5V1 and the simian line COS-7. Overall, the rank order for the effect of changes to the base 3' to UAG was C < G = U < A. This study confirms and extends earlier findings that in mammalian cells 3' C supports efficient nonsense suppression while 3' A is unsympathetic for read-through at nonsense codons. The rules for the mammalian codon context effect on nonsense suppression are therefore demonstrably different from those in E. coli.

Effect of aging and chronic angiotensin I converting enzyme inhibition on the endothelial function of the mesenteric arterial bed of the rat

Endothelial function was studied in perfused mesenteric arterial bed preparations removed from 6, 12, 24, or 30 month-old, male, normotensive rats. Half of the animals were treated with a hypotensive dose of an angiotensin I converting enzyme (ACE) inhibitor (perindopril, 1 mg/kg/day, p.o.) from 6 months onwards. Disruption of endothelium produced a fall in baseline perfusion pressure in all animals except 30-month old controls, suggesting that the maintenance of baseline tone by endothelial vasoconstrictor(s) is impaired with age. Physiologic antagonism of norepinephrine-induced vasoconstriction by the muscarinic agonist carbachol was impaired in 30-month old controls. Norepinephrine-induced vasoconstriction increased following disruption of endothelium, suggesting that norepinephrine-induced release of endothelium-derived relaxing factor attenuates vasoconstriction. This mechanism was impaired in 30-month old controls. Chronic ACE inhibition postponed the age-related decrease in vasodilator and vasoconstrictor endothelial functions, either directly or indirectly via the hypotensive action of such treatment.

Intracellular concentrations of fura-2 and fura-2/am in vascular smooth muscle cells following perfusion loading of fura-2/am in arterial segments

A new method for the determination of tissue concentrations of Fura-2 and Fura-2/AM was developed based upon acetonitrile extraction followed by RP-HPLC separation (using tetrahexylammonium as counter-ion), post-column alkaline hydrolysis of Fura-2/AM, and fluorimetric detection. The detection limit was 1.2 nM and 1 nM for Fura-2 and Fura-2/AM, respectively. When this technique was applied to perfusion-loaded segments of the rat tail artery, intracellular concentrations of Fura-2 determined by tissue disruption were 10 times those obtained by comparing the increase in fluorescence at the isoemissive point (following loading), with a calibration curve for Fura-2. Loading conditions of 90 min at [Fura-2/AM]e = 5 microM were optimal in terms of [Fura-2]i which attained a concentration not significantly different from [Fura-2/AM]e. Under such conditions, however, Fura-2/AM also accumulated in the arterial wall. Although incompletely de-esterified, Fura-2/AM metabolites produced by in vitro incubation of Fura-2/AM with pig liver esterases could be easily detected, fluorescent forms of Fura-2 with a different sensitivity for calcium were not detected in arterial extracts.

A comparison of laparoscopic versus open splenectomy in children

Laparoscopic operative procedures are gaining wider acceptance in pediatric patients. Although laparoscopic splenectomy is being performed more frequently, no studies to date have compared this procedure with the standard open technique with respect to operative outcomes. We performed a case control study of seven laparoscopic splenectomies and 14 open splenectomies. Two-tailed t test was used to compare the two groups for mean operative time, mean hospital stay, mean interval before tolerating a regular diet, and total parenteral narcotic dose in morphine equivalents. Operative time was significantly longer in the laparoscopic group (221 minutes vs 59 minutes, P < 0.001). Hospital stay, interval before tolerating a regular diet, and postoperative narcotic dose did not differ significantly between the two groups. In the laparoscopic group, one operation was converted to an open procedure secondary to bleeding complications. Three patients required mini-laparotomies for removal of extremely large spleens after completion of the dissection. Pediatric laparoscopic splenectomy does not appear to have advantages over the traditional method with regard to operative time, hospital stay, postoperative ileus, or postoperative pain. Larger studies, including cost analysis, are needed before major proposed advantages of laparoscopic splenectomy can be accepted.

Alcohol and liver fibrosis--pathobiochemistry and treatment

In Western societies roughly 50% of all cases of liver cirrhosis are related to alcohol abuse. The oxidative metabolite of ethanol, acetaldehyde, often in conjunction with viral or metabolic liver disease, is implicated as the major cause for liver fibrogenesis. Acetaldehyde damages cell membranes, initiates lipid peroxidation and forms noxious protein adducts, resulting in the activation of Kupffer cells and perisinusoidal lipocytes/portal fibroblasts. The activation of lipocytes and fibroblasts to a proliferative and collagen-producing myofibroblast-like phenotype is triggered by the release of fibrogenic factors such as platelet-derived growth factor (PDGF) and transforming growth factor-beta (TGF-beta) from the activated Kupffer cells. Due to the socioeconomic burden inflicted by cirrhosis, antifibrotic treatment is urgently needed. Strategies to prevent or reverse cirrhosis must interrupt the continuous process of pathological wound healing in the liver. An antifibrotic effect has been demonstrated for the interferons, prostaglandins E and relaxin. Polyunsaturated lecithin, silymarin and ursodeoxycholic acid, agents with a high hepatotropism and a good safety-profile, appear to have antifibrotic properties. Targeted approaches include the specific removal of matrix-bound fibrogenic growth factors and the induction of stress-relaxation of the activated mesenchymal cells by biologically active matrix-peptides and their stable analogues. Since serum tests for the non-invasive assessment of collagen synthesis and degradation in the liver are now available, rapid progress in the development and clinical application of antifibrotic drugs can be anticipated.

Ontogeny of membrane cofactor protein: phenotypic divergence in the fetal heart

Human adult cells are protected from complement-induced damage in part by membrane cofactor protein (MCP, CD46). To examine fetal characteristics which might influence autoantibody-mediated diseases acquired in utero, such as heart block in neonatal lupus, the tissue expression of MCP was studied. Using a high ratio of acrylamide:bisacrylamide, immunoblots of tissues from six fetuses (aged 19-24 weeks) probed with rabbit anti-MCP antibodies revealed a band at 60 KD in addition to the known 65 KD and 55 KD isoforms which comprise the codominant allelic system of MCP. Five fetuses expressed the most common MCP polymorphism (predominance of the 65 KD isoform, upper band alpha-phenotype) in the kidney, spleen, liver and lung. In contrast, all hearts from these five fetuses demonstrated a different pattern in which there was a marked decrease in the intensity of the 65 KD band and accentuation of the lower molecular weight bands. In a sixth fetus, which expressed the second most common polymorphism (equal expression of the 65 KD and 55 KD MCP isoforms, alpha beta-phenotype), the heart was similar to the other tissues. These studies confirm the expression of MCP in early gestational life. Preferential expression of the MCP beta-isoform in the majority of fetal hearts irrespective of the phenotype of other organs, suggests tissue-specific RNA splicing or post-translational modification which may relate to autoantibody-mediated injury in diseases such as neonatal lupus.

Severity of hypoxia predicts response to nitric oxide in a porcine pulmonary hypertension model

Although inhaled nitric oxide (NO) has been variably successful in resolving pulmonary hypertension in neonates, children, and adults, no parameters predictive of response to this therapy have been elucidated. We conducted an animal study to determine if severity of hypoxia can predict magnitude and sustenance of response to inhaled NO therapy. Seven Yorkshire swine weighing 11 to 20 kg underwent 16 experiments, each consisting of four phases: Phase 1: Control period of ventilation on FIO2 .3; phase 2: Hypoxic period on FIO2 .10 to .15, establishing pulmonary hypertension; phase 3: Treatment period with NO starting at five parts per million (ppm), doubling dose every 10 min to 80 ppm; phase 4: Posttreatment observation period after discontinuation of NO while maintaining hypoxia for 1 hour or until circulatory failure or pulmonary hypertension of pre-NO magnitude developed. Each animal underwent a maximum of three experiments in random order of hypoxia severity before sacrifice with pentobarbital overdose. Continuous hemodynamic parameters, intermittent cardiac output and pulmonary capillary wedge pressure, and intermittent arterial blood gas analyses were obtained through pulmonary and systemic artery catheters placed by femoral cutdown. Pulmonary and systemic vascular resistances (PVR and SVR) were calculated by standard formulas. Experiments were divided into two groups (n = 8 in each): group 1 with severe hypoxia (PaO2, 25 to 35) and group 2 with moderate hypoxia (PaO2, 36 to 65). Data for all hemodynamic parameters were expressed as mean percentage change from baseline (phase 1) +/- SEM under each set of conditions, and the two groups were compared by two-way analysis of variance and covariance adjusted for order of experimentation.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of chronic ANG I-converting enzyme inhibition on aging processes. V. Intracellular calcium-vasoreactivity coupling

Age-related changes in intracellular calcium ([Ca2+]i)-vasoreactivity coupling efficiency (i.e., perfusion pressure divided by [Ca2+]i) were studied in vitro in tail arteries of male, normotensive, WAG/Rij rats aged 6, 12, 24, or 30 mo; one-half of these were chronically treated with the angiotensin I-converting enzyme inhibitor (ACEI) perindopril (1 mg.kg-1.day-1 orally) from 6 mo onward. Arterial segments were perfused at a constant flow rate (perfusion pressure taken as an index of arterial tone) and loaded with the acetoxymethyl ester of fluorescent dye fura 2 (fura 2-AM). Increases in [Ca2+]i were measured simultaneously with vasoconstriction after stimulation with a depolarizing hyperkalemic solution or the agonists norepinephrine or serotonin. Age had no effect on increases in [Ca2+]i vasoconstrictor responses, or electromechanical coupling efficiency (hyperkalemic solution). Increases in [Ca2+]i after agonists were similar in all groups, but vasoconstrictor responses and pharmacomechanical coupling efficiency decreased with age. ACEI had no effect on vasoconstriction or [Ca2+]i signals. In conclusion, coupling efficiency after agonist stimulation decreased with age; ACEI had no effect on coupling efficiency.

Reduction of infant myopia: a longitudinal cycloplegic study

Changes of cycloplegic retinoscopy refraction from 8.5 to 38.5 months of age were compared in two infant groups in the Cambridge population: "infant myopes", having at least one myopic axis (0 to -3.5 D inclusive), and a second, "control" group with low hyperopia (< or = +3.5 D). Cycloplegia eliminated the variable accommodation of infants. The myopic group showed a significant emmetropization of the mean spherical equivalent towards low hyperopia by 3 yr. There was no significant change in the control group's mean spherical equivalent power. Both groups showed a significant reduction in astigmatism with age. Analysis of the vertical and horizontal powers showed significant "emmetropization" of these meridians, in both groups, towards low hyperopia from 8.5 to 38.5 months. These meridional emmetropization changes were significant for both With-the-Rule and Against-the-Rule astigmatism.

Cytokines modulate interleukin-6 production by human salivary gland cell line

The ability of HrTNF-alpha, HrIL-1 beta, and HrIFN-gamma to modulate IL-6 production by cultured human salivary cell line (HSG) was examined. IL-6 activity was measured by the hybridoma growth factor biologic activity. HrTNF-alpha had a significant dose-dependent effect, whereas HrIL-1 beta and HrIFN-gamma had moderate and minor effects, respectively. Maximal effect (920 units) was noted when cytokines were applied in combination (1000 units HrIFN-gamma and 20 units HrTNF-alpha) and incubated with human salivary gland cells for 72 hr. The same combination of cytokines had also a marked inhibitory effect (70% of control) on human salivary gland cell growth. This is the first report of these concomitant phenomena in a human cell line originating from salivary tissue.

Crystallization and preliminary X-ray analysis of a mutant duck delta II crystallin

A duck delta II crystallin mutant, where histidine 178 has been replaced by an aspartic acid residue, has been purified from a bacterial expression system and subsequently crystallized. The crystals grow as flat plates, with unit cell dimensions a = 94.1 A, b = 99.9 A, c = 108.7 A and beta = 102 degrees. The crystals exhibit the symmetry of space group P2(1) and diffract to a minimum d-spacing of 2.8 A resolution. On the basis of density calculation four monomers (one tetramer) are estimated to be present in the asymmetric unit (Vm = 2.5 A3/Da). Self-rotation functions clearly show the presence of 222 non-crystallographic symmetry.

Sympathetic neurotransmission in the tail artery of aging rats

1. Age-related changes in noradrenergic neurotransmission in the tail arteries of three rat strains: outbred Wistar (WI/Ico), inbred Wistar (WAG/Rij) and inbred Fischer (F344) have been compared in the present study. 2. The arterial noradrenaline content varied from 5 to 10 ng mg-1 wet weight amongst young (3 to 6-month old) representatives of each strain, but did not change with age. As protein content increased in senescent rats (24-month old) by 30-40%, arterial tissue growth would not appear to receive a concomitant increase in sympathetic growth leading to relative, age-related, structural sympathectomy in all strains. 3. The vasoconstrictor response to transmural electrical stimulation was diminished in adult and senescent rats of all strains. 4. As far as could be judged from the increase in noradrenaline release following perfusion with the alpha-adrenoceptor antagonist, phentolamine (1 microM), the presynaptic alpha 2-adrenoceptor-mediated inhibition of noradrenaline release was intact in old representatives of all strains. 5. With blockade of the two main systems which control noradrenaline release in the rat tail artery, viz, neuronal reuptake with cocaine (4 microM) and presynaptic alpha 2-adrenoceptors with phentolamine (1 microM), stimulation-evoked release of noradrenaline was similar at all ages and in all strains. This suggests that in the rat tail artery the basic mechanism of neuronal release of noradrenaline is not functionally modified by aging. 6 We conclude that as sympathetic nerve terminals are apparently intact in all three strains of senescent rats used, the age-associated deficit of alpha-adrenergic control of vascular function is postsynaptic in nature.

Evidence for a tropic role of brain-derived neurotrophic factor in transplanted embryonic retinae

Developing retinal axons must follow a stereotypic course directing them to the subcortical visual centres which on arrival they must recognise. Transplantation studies suggest that local substrate cues close to the surface of the brainstem and diffusible factors emanating from the target region are important. To test a role for diffusible factors, we transplanted retinae to the cerebral cortex and have shown that outgrowth can be promoted by BDNF secreting fibroblasts.

Effect of chronic ANG I-converting enzyme inhibition on aging processes. IV. Cerebral blood flow regulation

Age-related changes in systemic arterial blood pressure, basal cerebral blood flow (CBF), and CBF regulatory capacity were investigated in awake 6-, 12-, 24-, and 30-mo-old male Wistar (WAG/Rij) rats, one-half of which received the angiotensin I-converting enzyme inhibitor (ACEI) perindopril from 6 mo onward. There was no age-dependent change in mean arterial blood pressure, basal CBF, or cerebrovascular reactivity to hypercapnia, but the lower limit of CBF autoregulation rose from 70 mmHg at 6 and 12 mo to 90 mmHg in 24- and 30-mo-old animals. ACEI lowered mean arterial blood pressure but had no effect on basal CBF or on cerebrovascular reactivity to hypercapnia. ACEI shifted the lower limit of CBF autoregulation to a 20-mmHg-lower level in 12- and 24-mo animals but not in rats treated for 2 yr, i.e., from the ages of 6 to 30 mo. In conclusion, the main age-related change in CBF regulation was an increase in the lower limit of CBF autoregulation to a higher blood pressure level. Treatment with ACEI partially restored the lower limit of CBF autoregulation.

Effect of chronic ANG I-converting enzyme inhibition on aging processes. III. Endothelial function of mesenteric arterial bed of rat

Age-related changes in endothelial (E) function were studied in mesenteric arterial bed (MAB) preparations removed from male, normotensive, WAG/Rij rats. At the age of 6 mo, one-half of the animals was assigned to chronic treatment with a hypotensive dose of an angiotensin I (ANG I)-converting enzyme inhibitor (ACEI; perindopril, 1 mg.kg-1.day-1 po). Animals were killed at 6, 12, 24, or 30 mo of age; the MAB was perfused in vitro, perfusion pressure (PP) being taken as an index of arteriolar tone. Disruption of E function produced a fall in baseline PP in all groups except 30-mo-old rats, suggesting that 1) baseline tone is maintained by the release of E vasoconstrictor factor(s) and 2) this mechanism is impaired in 30-mo-old rats. The muscarinic agonist, carbachol, antagonized vasoconstriction produced by norepinephrine (NE) in the presence of E. This mechanism was impaired in 30-mo-old rats. NE vasoconstriction increased following disruption of E, suggesting that NE release of endothelium-derived relaxing factor attenuates vasoconstriction. This mechanism was impaired in 30-mo-old rats. Chronic ACEI postponed the age-related decrease in E function, possibly due to a direct effect, or an indirect effect via the prolonged hypotensive action of such treatment.

Mutations to nonsense codons in human genetic disease: implications for gene therapy by nonsense suppressor tRNAs

Nonsense suppressor tRNAs have been suggested as potential agents for human somatic gene therapy. Recent work from this laboratory has described significant effects of 3' codon context on the efficiency of human nonsense suppressors. A rapid increase in the number of reports of human diseases caused by nonsense codons, prompted us to determine how the spectrum of mutation to either UAG, UAA or UGA codons and their respective 3' contexts, might effect the efficiency of human suppressor tRNAs employed for purposes of gene therapy. This paper presents a survey of 179 events of mutations to nonsense codons which cause human germline or somatic disease. The analysis revealed a ratio of approximately 1:2:3 for mutation to UAA, UAG and UGA respectively. This pattern is similar, but not identical, to that of naturally occurring stop codons. The 3' contexts of new mutations to stop were also analysed. Once again, the pattern was similar to the contexts surrounding natural termination signals. These results imply there will be little difference in the sensitivity of nonsense mutations and natural stop codons to suppression by nonsense suppressor tRNAs. Analysis of the codons altered by nonsense mutations suggests that efforts to design human UAG suppressor tRNAs charged with Trp, Gln, and Glu; UAA suppressors charged with Gln and Glu, and UGA suppressors which insert Arg, would be an essential step in the development of suppressor tRNAs as agents of human somatic gene therapy.

Reduction of endothelial function with age in the mesenteric arterial bed of the normotensive rat

1. Age-related changes in endothelial vasodilator function were studied in an in vitro preparation of the mesenteric arterial bed removed from male, normotensive, Wistar rats. 2. Animals were killed at 2, 12 or 22 months of age, the superior mesenteric artery was cannulated and the gut removed. The mesenteric arterial bed was perfused at a constant flow rate of 4 ml min-1 and perfusion pressure was taken as an index of arteriolar tone. 3. The muscarinic agonist, carbachol, antagonized noradrenaline-induced vasoconstriction in the presence, but not in the absence, of endothelium. This cholinoceptor agonist-induced release of endothelial-derived relaxing factor (EDRF) was impaired in 22 month old rats. 4. Noradrenaline-induced vasoconstriction increased following removal of endothelium suggesting that agonist-induced release of EDRF attenuates vasoconstrictor responses to noradrenaline measured in the presence of endothelium. 5. Removal of endothelium had less effect on noradrenaline-induced vasoconstriction in old rats suggesting once again that agonist-induced release of EDRF is impaired in old rats. 6. The noradrenaline dose-response curve established in the presence of endothelium was shifted to the left in 22 month old rats. 7. In conclusion, aging in the rat appears to lead to a reduction in endothelial vasodilator function in a resistance vessel.

Asthma at the interface: bridging the gap between general practice and a district general hospital

A clinic supervised by a nurse, using principles originally developed in general practice, was established in the paediatric department of a district general hospital. A randomised controlled study was conducted comparing children admitted with asthma or attending outpatients who were given a patient education programme and self management plan (intervention group) with a control group. The study comprised 91 patients aged 3-14 years admitted for asthma or attending a hospital outpatient department from November 1989 to November 1990. Seventy seven patients completed the study and kept diaries for a median of 283 days. Patients in the intervention group had significantly less restriction of activity (95% confidence interval (CI) -0.27 to -0.01) and fewer episodes of peak flow below 30% of best (95% CI 0.03 to 1.17). Patients in the intervention group were more likely to make the correct response to an acute exacerbation of their asthma than the control group (71% v 47%, 95% CI 9.51 to 39.1). The intervention group had fewer school absences and fewer home visits by a general practitioner. There was an increase in the readmission rate for the intervention group. A subgroup of patients who self managed by doubling their use of inhaled steroids during an exacerbation performed better than those patients who only increased their bronchodilator or were managed on salbutamol or sodium cromoglycate alone. Improvements in patient follow up and the structure of the self management plans used, particularly changing the peak flow level at which inhaled steroids are doubled, may further improve the outcome of patients attending the asthma clinic.

Estimation of myocardial interstitial norepinephrine release after brain death using cardiac microdialysis

Brain death is a pathophysiological condition associated with major hemodynamic changes, temporary myocardial ischemia, and histological damage of the heart. These modifications could be related to a major local release of norepinephrine from myocardial sympathetic nerve endings leading to norepinephrine cardiotoxicity. This study was designed to evaluate the utility of cardiac microdialysis to measure interstitial myocardial norepinephrine release resulting from brain death. The dialysis probe consisted in a 10 x 0.20-mm dialysis fiber with a 18,000 mol wt cutoff. Dialysis probes were implanted into the right and left ventricular walls of the beating heart in anesthetized pigs and perfused with Ringer solution at 2 microliters/min. Dialysate norepinephrine concentration was measured using HPLC with electrochemical detection. The relative recovery rate of norepinephrine in vivo was 34 +/- 4%. Interstitial fluid concentrations were obtained using the following formula: [C]interstitium = [C]dialysate/Recovery in vivo. After brain death, a transient increase in interstitial norepinephrine concentration was observed (from 0.74 +/- 0.20 to 4.50 +/- 0.60 ng/ml and 0.76 +/- 0.20 to 6.2 +/- 0.9 ng/ml in left and right ventricle, respectively, P < 0.01) which far exceeded plasma level increase (from 0.50 +/- 0.10 ng/ml to 0.91 +/- 0.20 ng/ml, P < 0.05). This increase in myocardial norepinephrine was, moreover, biphasic, with a second peak occurring 40 min after brain death. The present study confirms the onset of a dramatic increase in cardiac norepinephrine release from myocardial nerve endings following brain death, and demonstrate the utility of the new cardiac microdialysis technique to assess changes in interstitial fluid content.

Increased arterial distensibility induced by the angiotensin-converting enzyme inhibitor, lisinopril, in normotensive rats

1. We investigated possible structural correlates of the beneficial effect of chronic angiotensin-converting enzyme inhibition (ACEI) with lisinopril on the aortic distensibility of normotensive rats. 2. Experiments were performed in young (4-month old), normotensive, Wistar rats which received lisinopril in their drinking water (0.9 or 9 mg kg-1 day-1) for 9 months. 3. Following ACEI treatment, rats were pithed and aortic pulse wave velocity was measured during the progressive rise in mean arterial blood pressure produced by i.v. infusion of the alpha 1-adrenoceptor agonist, phenylephrine. The slope of the regression line relating aortic pulse wave velocity to mean arterial blood pressure was taken as an index of aortic distensibility. Following this, the aorta was fixed in situ at a normotensive pressure level and histomorphometry was performed. We also measured the calcium content of the aortic wall by atomic absorption. 4. The lower dose of lisinopril failed to lower systolic arterial blood pressure (unanaesthetized rat) or mean arterial blood pressure (pithed rat). Chronic ACEI with the higher dose of lisinopril lowered both systolic arterial blood pressure (104 +/- 6 mmHg, controls 133 +/- 4 mmHg, unanaesthetized), and mean arterial blood pressure (27 +/- 1 mmHg, controls 34 +/- 2 mmHg, pithed). 5. Although the lower dose of lisinopril did not lower blood pressure, it did improve aortic distensibility as revealed by a fall in the slope relating aortic pulse wave velocity (Y) to mean arterial blood pressure (X). Values were 5.7 +/- 0.7, 3.8 +/- 0.6 and 2.7 +/- 0.3 in controls, and in low and high ACEI groups, respectively. 6. Lisinopril treatment did not modify the calcium content, the internal and external diameters or the medial thickness of the aorta. Chronic ACEI did, however, increase the thickness of the medial elastic fibres (controls 3.55 +/- 0.05 microm, low dose ACEI 4.05 +/- 0.15 gm (P<0.05), and high dose ACEI4.18 +/- 0.15 microm (P<0.05)).7. In conclusion, we would suggest that ACEI treatment with a low dose of lisinopril can decrease aortic stiffness via a pressure-independent mechanism which possibly involves an effect of ACEI on elastic fibres.

Vascular Ca overload produced by vitamin D3 plus nicotine diminishes arterial distensibility in rats

In humans, aging produces many structural changes in blood vessels, one of the most pronounced being arterial calcium overload. Simultaneously arteries become increasingly rigid. The slow evolution of the two processes renders it difficult to evaluate the importance of vascular calcium overload in the development of decreased compliance. To gain insight into this relationship, rapid vascular calcium overload was produced by treating young rats with vitamin D3 and nicotine. When rats were allowed 16 days or longer to recover from such treatment, analysis of plasma parameters revealed no overt toxicity, and growth rate was similar to that of controls. Pronounced calcium overload was seen primarily in compliance arteries. Changes in systemic arterial compliance, characteristic impedance, pulse-wave velocity, and carotid compliance all reflected a substantial increase in arterial rigidity. Linear regression analysis revealed significant correlations between the various indicators of arterial distensibility and arterial calcium content. In conclusion, treatment of young rats with vitamin D3 and nicotine may provide a suitable model with which to investigate how calcium overload is involved in the induration of compliance arteries.

Modulation by the endothelium of sympathetic vasoconstriction in an in vitro preparation of the rat tail artery

1. The influence of the endothelium on transmural electrical stimulation was investigated in isolated and perfused segments of the rat tail artery. Noradrenaline release (NA, quantified by h.p.l.c.-electrochemical detection) and changes in perfusion pressure (PP, measured at constant flow rate) were simultaneously recorded in unstimulated and stimulated arterial segments, in the absence and in the presence of drugs. The ratio PP/NA release (mmHg pg-1) was taken as an index of the noradrenergic effectiveness. 2. Removal of the endothelium produced an increase in NA release and PP, in unstimulated and stimulated arteries. This can be taken as evidence of an endothelium-derived inhibitory factor (EDIF) acting at the prejunctional level, inhibiting NA release. Furthermore, in unstimulated arteries, the ratio PP/NA release decreased suggesting the existence of an endothelium-derived contracting factor (EDCF). 3. Perfusion of arteries with N omega-nitro-L-arginine methyl ester (L-NAME, 10 microM) or methylene blue (MeB, 0.5 microM) had no effect on PP or NA release in unstimulated arteries. In stimulated arteries, both drugs potentiated the increase in PP without changing NA release and therefore, led to an increase in noradrenergic effectiveness. After removal of the endothelium, neither L-NAME nor MeB affected the increases in PP and NA release following electrical stimulation. 4. Carbachol (1 microM) attenuated both NA release and the increase in PP during electrical stimulation, and increased the ratio PP/NA release. L-NAME and MeB did not modify the inhibitory effect of carbachol on NA release, or the facilitatory effect of carbachol on the noradrenergic effectiveness. 5. Angiotensin II (All, 0.1 MicroM) potentiated the increase in PP, without modifying NA release following electrical stimulation, and facilitated the vasoconstriction induced by perfusion of NA. In the absence of endothelium, All potentiated both the increase in PP and NA release in arteries stimulated electrically but had no effect on the vasoconstriction induced by perfusion of NA. This suggests an endothelium dependent activity of All in this preparation.6. These findings suggest that, in the rat tail artery, sympathetic vasoconstriction is modulated by three endothelial factors: (1) nitric oxide (NO), the release ot which seems NA-dependent; (2) EDCF,predominant in the unstimulated state, the release of which; can be stimulated by All; and (3) EDIF,unmasked by removal of the endothelial layer, the release of which can be stimulated by All.

Intracellular free Ca2+ and vasoconstriction determined simultaneously in the perfused rat tail artery

To measure, simultaneously, intracellular free Ca2+ ([Ca2+]i) and vasoconstriction in a perfused vessel, we used the fluorescent Ca2+ indicator fura 2 with a dual-wavelength excitation method. One-centimeter-long segments of the caudal artery were dissected from 12-mo-old male Wistar rats. The endothelium was removed by gentle rubbing. The artery was mounted in a specially constructed spectrofluorometer cuvette, perfused with oxygenated physiological saline solution at 37 degrees C, and loaded by perfusion with fura 2 acetoxymethyl ester (5 microM) over a 90-min period. This paper is a description of the technique and the experiments that validate it as a useful method for examining Ca(2+)-related vascular reactivity in an intact perfused vessel.

Hemispheric asymmetries for an inspection time task: a general left hemisphere temporal advantage?

Two thematic versions of an inspection time task were administered to 18 normal, right-handed subjects. For both tasks, subjects were required to make a categorical discrimination related to the length of two lines. In one version of the task (time task), difficulty was manipulated by varying the exposure duration of the lines. In the other version (length task), difficulty was manipulated by varying the degree to which one line was shorter than the other. The time task was designed to measure the temporal acuity of the observer while the length task was used to gauge subjects' capacity for the same categorical discrimination; independent of temporal acuity. Thus, the two tasks were designed to dissociate the categorical and temporal aspects of the inspection time task. Divided visual field techniques revealed a significant left hemisphere (LH) advantage for the time task, but no asymmetry for the length task. These results could not be accounted for in terms of the categorical nature of the representation. A model, related to the LH's predisposition for the detection of fine temporal events provided a more satisfactory account of the results.

[Myoplasmic calcium-vasoconstriction coupling in the perfused caudal artery of adult spontaneously hypertensive rats. Effect of antihypertensive treatment]

In order to investigate whether smooth muscle intracellular calcium levels ([Ca2+]i) are related to hypertension and drug-induced changes in blood pressure, we studied basal perfusion resistance and basal [Ca2+]i and increases in perfusion pressure and [Ca2+]i using the fluorescent dye, fura-2 (dual wavelength excitation) in perfused tail artery. These were removed from 6 month old SHR previously treated (CAP + HCZ) for 10 weeks with captopril plus hydrochlorothiazide (44 and 22 mg/kg/day po, respectively). Separate groups received captopril (CAP) or hydrochlorothiazie (HCZ) alone, at similar doses, or no treatment (SHR). A fifth group of WKY normotensive rats did not receive any drug. Following determination of systolic arterial pressure (SAP) in awake rats, tail artery segments were removed and perfused at a constant flow rate with physiological salt solution plus fura-2/AM. Basal resistance and [Ca2+]i were determined. Then a dose-response curve for calcium chloride in the presence of a depolarizing concentration of potassium chloride was constructed. SAP was lowered in groups CAP + HCZ or CAP, but not in the group HCZ. Basal [Ca2+]i were similar in treated and untreated SHR and in WKY. Basal resistance to flow was lower in groups CAP + HCZ or CAP, and in WKY, than in untreated SHR. In depolarized arterial segments, vasconstrictor responses to perfusion with calcium chloride were lower in groups CAP + HCZ or CAP, and in WKY. Increases in [Ca2+]i were diminished in WKY rats. SAP measured in awake SHR and WKY was significantly correlated to basal and stimulated intracellular calcium-vasoreactivity coupling measured in vitro.

Prevalence and longitudinal study of breast masses in adolescents

This study examined the prevalence and outcome of breast masses in adolescent females and compared these teens to those without breast masses. A longitudinal study of adolescents with breast masses was conducted from October 1984 through January 1990. The prevalence of discrete breast masses in the 13-month study period was 13/400 (3.25%) among new female patients. The mean length and width of the masses were 2.8 and 1.9 cm; 86% had a solitary mass. Of 61 diagnosed with breast masses, 39 were followed for up to 40 months (mean, 7 months). Teens with a mass were older (16.8 versus 15.1 years, p < 0.001) and had a greater chance of a family history of breast disease (26% versus 10.5%, p < 0.05) than those without a breast mass. Of 39 teens returning for at least one follow-up visit, 10 had a clinical diagnosis of "fibrocystic changes." Of these, the lesions resolved in six. Of the 29 teens with a discrete mass on examination, 7 underwent surgery and were found to have fibroadenomas. Nine of the 29 teens had masses which resolved over 1-12 months, six teens had masses which remained unchanged over 3-40 months, while four had masses which became smaller, and two had masses which became larger. One teen with mastitis improved. Eighteen underwent ultrasonographic examination at the breast. Of the 12 teens found to have a solid mass on ultrasound, none had a mass that resolved on follow-up examination.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo cerebrovascular reactivity in Wistar and Fischer 344 rat strains during aging

Basal cerebral blood flow (CBF) and CBF regulation after hypercapnia and hypotensive hemorrhage were investigated using H2 clearance in the frontal cortex of awake 2-, 14-, or 23-mo-old Wistar or Fischer 344 rats. Basal CBF decreased in old Wistar but not in mature Wistar (old 64.4 +/- 2.8, mature 87.6 +/- 2.6, young 79.6 +/- 2.2 ml.min-1 x 100 g-1) or in old Fischer 344 (old 71.9 +/- 2.9, young 73.3 +/- 1.6 ml.min-1 x 100 g-1) rats. Cerebrovascular reactivity to hypercapnia decreased in mature and old Wistar (old 2.1 +/- 0.3, mature 3.1 +/- 0.7, young 7.0 +/- 2.1 ml.min-1 x 100 g-1 x mmHg-1) but not in old Fischer 344 rats (old 4.6 +/- 1.4, young 4.9 +/- 0.9 ml.min-1 x 100 g-1 x mmHg-1). The lower limit of CBF autoregulation increased by 20 mmHg during maturation and/or aging in the two strains. Because blood gases and pH evolved similarly in both strains, we postulate that differences in cerebrovascular structure and/or function explain the differences in CBF regulation in the older representatives of the two strains.