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Biomedical subjects

A Hill

Publications and source records attributed to A Hill.

At least 271 records · Page 15Linked to original sources
PubMed1983

On the combination of alpha- and beta-adrenoceptor blockade in hypertension.

A randomized double-blind crossover trial was conducted in 20 patients with moderate to severe hypertension to compare the efficacy of labetalol, which combines alpha- and beta-adrenoceptor blocking properties, with that of metoprolol alone or in combination with prazosin. After placebo for 1 wk, active medication was given in two 6-wk phases. During one phase, metoprolol (100 to 400 mg/day) was given with prazosin (2 to 4 mg/day) as an option in the last 3 wk, whereas during the other phase, labetalol (200 to 1000 mg/day) was given alone. Satisfactory control of supine blood pressure was obtained in 10 patients with metoprolol and in another four patients after the addition of prazosin. During the labetalol phase, blood pressure control was achieved in 11 of 19 patients tested. Gastrointestinal disturbances, nasal congestion, impotence, failure to ejaculate, scalp tingling, and headache were more prevalent in the labetalol phase than in the other. In four cases these occurred in patients who did not require prazosin. Supine, erect, and exercise pulse rates were reduced by both metoprolol with or without prazosin and by labetalol; the effects were less in the labetalol phase. These differences could arise from an action of labetalol on cardiac presynaptic alpha-adrenoceptors. Adjunctive use of prazosin in nonresponders to metoprolol increases the response rate and avoids unnecessary deployment of alpha-adrenoceptor blockade in patients whose blood pressure can be controlled by beta-blockade alone.

Adult↗
PubMed1983

Mycoplasma pulmonis infection in the brains of rodents.

Mycoplasma pulmonis was frequently present in the brains of both naturally and experimentally infected rats. Recovery of mycoplasmas from the brain was more common than from the lungs, except when there was a mixed respiratory tract infection or when immunodeficient rats were used and they developed chronic respiratory disease. After intranasal infection the mycoplasmas could be recovered from the olfactory lobes before the rest of the brain. Most of the organisms were demonstrated in small groups in the sinuses and blood vessels of the brain, apparently adhering to the epithelium; a few were present in the lumen. The presence of some mycoplasmas outside the blood vessels and attached to cells in tissue showed that the blood-brain barrier can be crossed. Three days after intranasal inoculation, most organisms lined the nasal mucosa, but a few were seen close to neurons, on cells in the olfactory lobes, and in blood vessels.

Animals↗
PubMed1983

Thin ribs on chest X-ray: a useful sign in the differential diagnosis of the floppy newborn.

The significance of thin ribs among 26 newborns diagnosed as having neuromuscular disease is discussed. 19 had a chest X-ray. Thin ribs were observed in three of seven with congenital myotonic dystrophy, in two of four with myotubular myopathy and in one of five with spinal muscular atrophy. The ribs were normal in one case of nemaline myopathy and two cases of non-specific myopathy. Polyhydramnios was recorded in four of the six cases with thin ribs. Ventilatory support frequently was required for these infants. The observation of thin ribs on X-ray is highly suggestive of neonatal neuromuscular disease, and is neither specific for nor invariable in congenital myotonic dystrophy.

Diagnosis, Differential↗
PubMed1983

Induction of luteolysis in goats with prostaglandin F2 alpha.

On day 10 of each estrous cycle, 19 cycling does were given (IM) 1 of 3 dosage levels of prostaglandin F2 alpha (PGF2 alpha) or saline solution. After injections, goats were observed twice daily for behavioral estrus, and serum concentrations of progesterone (P4) were determined from daily blood collections to measure response to treatment. Every dose of PGF2 alpha (0.0165 mg/kg of body weight, 0.0275 mg/kg, and 0.0385 mg/kg) was administered during 20 estrous cycles, and 0.25 ml of saline solution was administered during 12 estrous cycles. Fourteen of 20, 15 of 20, 20 of 20, and 0 of 12 does exhibited signs of behavioral estrus within 96 hours of injections of 0.0165 mg of PGF2 alpha/kg, 0.0275 mg of PGF2 alpha/kg, 0.0385 mg of PGF2 alpha/kg, and saline solution, respectively. A decline in mean concentrations of peripheral P4 from 3.6, 3.8, 4.4, and 4.3 ng/ml to less than 1 ng/ml within 24 hours was observed in 15 of 20, 16 of 20, 20 of 20, and 0 of 10 does after injections of 0.0165 mg of PGF2 alpha/kg, 0.0275 mg of PGF2 alpha/kg, 0.0385 mg of PGF2 alpha/kg, and saline solution, respectively. The dosage level of 0.0385 mg of PGF2 alpha/kg (1.75 mg of PGF2 alpha/45.36 kg) was effective for induction of estrus in 100% of the does.

Animals↗
PubMed1983

Focal ischemic cerebral injury in the newborn: diagnosis by ultrasound and correlation with computed tomographic scan.

Ischemic brain injury in the newborn is a common cause of subsequent neurologic deficits seen in older children. Clearly, determination of severity and location of such injury is important for management and prognosis. Although ultrasound scanning of the brain has been used extensively in the premature infant for diagnosis of hemorrhagic lesions, its use in the term infant for recognition of ischemic cerebral lesions has not been reported. Four cases are described in which focal echodense areas were identified on ultrasound scan of the brain. These echodense areas on ultrasound corresponded to the appearance on computed tomographic (CT) scan of areas of decreased density which are known to represent ischemic cerebral injury. In three of the four cases there were focal neurologic findings and/or focal abnormalities on EEG. In two cases, real-time ultrasound scanning demonstrated changes in arterial pulsations in cerebral vessels in the area of the lesions. Thus in both, there was diminution in pulsations within the echodense areas and in one case, an increase in pulsations was observed at the periphery of the echodense lesion. Our data demonstrate the value of ultrasound scanning for assessment of the extent and location of focal cerebral ischemic lesions in the newborn. Such assessment permits assessment of prognosis.

Brain Ischemia↗
PubMed1983

Sister chromatid exchanges and cell division delays induced by diethylstilbestrol, estradiol, and estriol in human lymphocytes.

It had been found previously that exposure of human lymphocytes in vitro to diethylstilbestrol (DES), a synthetic estrogen and known human carcinogen, led to the induction of sister chromatid exchanges. More sister chromatid exchanges were induced in cells from pregnant women than from men. To see if the effects of DES could be induced by other estrogens, lymphocytes from a man and a pregnant woman were treated in vitro with the natural estrogens estradiol and estriol. These did not induce sister chromatid exchanges. To see if the presence of exogenous female hormones might be responsible for the increase in DES-induced sister chromatid exchanges seen in cells from pregnant women, lymphocytes from a man and a pregnant woman were also treated in vitro simultaneously with DES, estradiol, estriol, and progesterone. Treatments with these exogenous hormones did not alter the number of DES-induced sister chromatid exchanges. Our previous studies showed that DES also inhibits in vitro proliferation of lymphocytes. The results reported here show that estradiol also strongly inhibits this proliferation but that estriol is only a weak inhibitor. The cause of delayed cell proliferation induced by DES and estradiol was 2-fold: some of the cells were delayed in phytohemagglutinin-mediated blast cell transformation but, additionally, most cells had a prolonged cell cycle because of an extended G2 phase. These studies also showed that DES, but not estradiol or estriol, induced a low level of polyploidy in human lymphocytes.

Cell Cycle↗
PubMed1982

Osmosis: a bimodal theory with implications for symmetry.

A theory is advanced that volume transfer across a membrane pore during osmosis takes place in two modes: if solute is sterically excluded from the pore a pressure gradient is set up and viscous flow of solvent results; if solute can enter the pore then osmotic flow is a diffusive phenomenon, and there is no pressure gradient in any part of the pore to which solute has access, even at low concentration due to a repulsive wall field. As a consequence the reflexion coefficients sigma s and sigma f for osmosis and ultrafiltration are not equal, although equality is usually assumed to result from an underlying thermodynamic reciprocity; instead, the two coefficients represent essentially different processes. These results follow from three basic thermodynamic considerations which have usually been overlooked: (i) there is a qualitative difference between a permeable pore and an impermeable one, the latter having a discontinuity of solute activity at the mouth, which the former does not; (ii) the osmotic pressure within the pore is determined by the activity of solute not the concentration; (iii) the effective resistance to flow through a channel depends upon the nature of the régime, being different for diffusive and viscous flow. An expression for sigma s is derived and shown to be compatible with experimental data on polymer membranes and homoporous bilayers.

Cell Membrane↗
PubMed1982

Relationship of pneumothorax to occurrence of intraventricular hemorrhage in the premature newborn.

The relationship of pneumothorax to the occurrence of intraventricular hemorrhage (IVH) has been studied in the premature newborn. The major objective of the study was to determine whether the systemic hemodynamic changes that occur with pneumothorax are reflected in the cerebral circulation and whether these changes play a role in pathogenesis of IVH. Blood flow velocity was measured in the anterior cerebral arteries by a transcutaneous Doppler technique in nine infants who developed pneumothorax in the first 3 days of life. At the time of pneumothorax there was a marked increase in flow velocity, especially during diastole, and, with resolution of pneumothorax, flow velocity returned to normal levels over the ensuing hours. The changes in flow velocity correlated closely with systemic hemodynamic changes that occurred with pneumothorax, ie, and increase in mean systemic blood pressure, especially diastolic pressure. IVH, documented by serial ultrasound scans, was observed shortly after pneumothorax in the nine infants. The data thus demonstrate a marked increase in flow velocity in the cerebral circulation at the time of pneumothorax. This increase is of importance in the genesis of IVH as is suggested further by the occurrence of IVH soon after the cerebral hemodynamic changes.

Birth Weight↗
PubMed1982

Decrease in pulsatile flow in the anterior cerebral arteries in infantile hydrocephalus.

The effect of ventriculomegaly with or without elevated intracranial pressure (ICP) on pulsatile flow in the anterior cerebral artery has been studied by a noninvasive Doppler technique in 11 infants with hydrocephalus. The cause of hydrocephalus was intraventricular hemorrhage in nine infants, Arnold-Chiari malformation in one, and bacterial meningitis in one. The pulsatility index (PI) (inversely related to pulsatile flow) was calculated from the systolic and diastolic amplitudes of flow in the anterior cerebral artery. All 11 patients with elevated PI had marked ventriculomegaly, and all but two had raised ICP. Four patients with massive ventriculomegaly and elevated ICP had maximal PI (ie, 1.00). The finding of elevated PI with ventriculomegaly and normal ICP, observed in two patients, suggested that ventriculomegaly is a more critical factor than ICP in the pathogenesis of the impaired flow. Treatment of ventriculomegaly in seven patients resulted in a decrease in PI. Of the four untreated patients, three died and one was not available for further study. Compromised flow in the anterior cerebral artery may be a sensitive barometer of impending ischemic injury with evolving ventriculomegaly, particularly following intraventricular hemorrhage. The PI may be a valuable parameter for the study of the mechanism of brain injury and for determination of optimal timing of corrective intervention.

Cerebral Arteries↗
PubMed1982

Increased induction of sister chromatid exchange by diethylstilbestrol in lymphocytes from pregnant and premenopausal women.

Cultures of whole blood from pregnant women (4 to 6 months), premenopausal women, postmenopausal women, and normal men were grown in the presence of varying concentrations (1 x 10(-5) M, 2 x 10(-5) M, and 4 x 10(-5) M) of diethylstilbestrol (DES), a synthetic estrogen and known carcinogen, to see if it had sex-related cytogenetic effects. DES induced sister chromatid exchanges in lymphocytes from pregnant and premenopausal women but had only a small effect at the highest concentration (4 x 10(-5) M) in lymphocytes from men and postmenopausal women. At all concentrations, the average number of sister chromatid exchanges was higher in lymphocytes from pregnant women than in those from premenopausal women. In lymphocytes from both a man and a pregnant woman, DES strongly inhibited cell proliferation in vitro. When lymphocytes from a man and a pregnant woman were cocultured in the presence of DES, only the lymphocytes of the woman responded with an increase in sister chromatid exchanges. This indicated that there is no interaction between DES and a factor present in the blood but that DES acts directly on each cell.

Adult↗
PubMed1982

Hemorrhagic periventricular leukomalacia: diagnosis by real time ultrasound and correlation with autopsy findings.

Hemorrhage into areas of periventricular leukomalacia may occur and range in size from microscopic to massive. Hitherto, the definitive diagnosis has been made only at autopsy. A case is described in which the diagnosis of hemorrhagic periventricular leukomalacia was made antemortem by real-time ultrasound scanning and confirmed at autopsy. Periventricular/intraventricular hemorrhage, a more common hemorrhagic lesion, may extend into periventricular with matter in a location ventral and medial to hemorrhagic periventricular leukomalacia. Real-time ultrasound scanning is a safe and reliable means of defining the topography of these two hemorrhagic lesions and, thereby, of suggesting the correct diagnosis.

Brain↗
PubMed1981

Visceral larva migrans (toxocariasis) in Toronto.

A 7-year-old child was admitted to Toronto's Hospital for Sick Children in 1976 with symptoms and laboratory findings compatible with visceral larva migrans, a disease usually caused by Toxocara canis. This prompted a search for other cases seen at the hospital during the period 1952 through 1978. Only 18 cases were discovered that met at least three of six criteria and thus were considered possible or probably cases of the disease. Three possible cases of ocular toxocariasis during the same period were also uncovered. Fever was the commonest presenting symptom. Eosinophilia, leukocytosis and hyperglobulinemia were the most frequent laboratory findings. In view of the small number of cases found in 27 years at this large pediatric hospital with a broad referral base, it is concluded that visceral larva migrans poses little risk to the health of children in the Toronto area.

Adolescent↗
PubMed1981

Seizures, hypoxic-ischemic brain injury, and intraventricular hemorrhage in the newborn.

The review deals with neonatal seizures, perinatal hypoxic-ischemic brain injury, and neonatal intraventricular hemorrhage. neonatal seizures are the most prominent signals of the largest number of neonatal neurological disorders. The convulsive phenomena may be subtle. The predominant etiological process is hypoxic-ischemic encephalopathy. Prognosis is related primarily to the neurological disease responsible for the seizures. Treatment may be specific for the underlying disorder (e.g., glucose or calcium) or less specific (i.e., therapy with anticonvulsant drugs). Prompt control of the seizures is important to avoid brain injury secondary to the effects of the seizures on ventilation, perfusion, and brain metabolism. Hypoxic-ischemic encephalopathy in the newborn most often is a consequence of intrauterine asphyxia. Diagnosis depends primarily on recognition of the clinical syndrome but also on a variety of neurodiagnostic techniques, including radionuclide and CT brain scans. Prognosis is estimated best by a combination of clinical analysis and specialized neurodiagnostic studies. management is based principally on vigorous support, particularly of ventilation and perfusion, maintenance of adequate glucose influx, and control of seizures. Intraventricular hemorrhage is the most common type of neonatal intracranial hemorrhage. The neuropathology is characterized by bleeding from capillaries of the subependymal germinal matrix. Secondary rupture of the ependymal lining then causes intraventricular hemorrhage. Pathogenesis relates to the anatomy of the germinal matrix, the distribution and regulation of cerebral blood flow, and the structure and vulnerability of periventricular capillaries. Precise diagnosis requires a brain imaging procedure; portable, real-time ultrasound is the preferred approach for critically ill infants. Prognosis relates to the severity of the hemorrhage as well as any preceding hypoxic-ischemic insults and the subsequent occurrence of hydrocephalus. Choice of therapy for posthemorrhagic ventricular dilatation depends upon severity and rapidity of progression and ranges from close observation only to ventriculoperitoneal shunting.

Brain Ischemia↗
PubMed1981

The preparation of amino bile acid derivatives.

Bile acid derivatives have been prepared by reaction of their mixed anhydrides with diaminoethane. The new compounds have side chains modified by amide bond formation which extends the side chain by two carbon atoms and terminates in a primary amino group. Important properties of the new compounds are their solubility in acid, and their ability to act as nucleophiles in the carbodiimide reaction or mixed anhydride reaction. The derivatives have been used to prepare high molar ratio immunogens with bovine serum albumin and to prepare 125I labelled ligands for radioimmunoassay.

Bile Acids and Salts↗