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Biomedical subjects

C Hall

Publications and source records attributed to C Hall.

At least 199 records · Page 11Linked to original sources
PubMed1994

Prospective study of central nervous system function in amateur boxers in the United States.

Active amateur boxers from six US cities were studied in 1986-1990 to determine whether changes in central nervous system function over a 2-year interval (as evaluated by tests of perceptual/motor function, attention/concentration, psychomotor speed, memory, visuoconstructional ability, and mental control, measures of ataxia and brain-stem auditory evoked potentials, and electroencephalography) were associated with degree of participation in amateur boxing. A total of 484 participants were examined at baseline; 393 (81.2%) were examined 2 years later. At baseline, 22% of the participants had not yet competed in a bout; 9% had never competed in a bout by the second examination. Exposure was defined by number bouts, sparring-years, and sparring with a professional boxer. Very few statistically significant odds ratios were found between exposure and change in function. Significant tests of trend were found between the total number of bouts incurred before the baseline examination and changes in memory, visuoconstructional ability, and perceptual/motor ability. The significant trends for change in function in the latter two domains were primarily due to performance on the Block Design test, which was common to both test domains. No statistically significant associations were found between more recent bouts (after the baseline visit) and any functional domains, nor between bouts or sparring and any other outcome measures. The significant trends with past bouts, but not more recent bouts, may reflect the need for a long latency period before effects are manifest. Alternatively, given changes in safety practices, the observed association may be related to more severe exposure from bouts that occurred before 1986, when new safety measures were imposed.

Adolescent↗
PubMed1994

The plasma concentration of N-terminal proatrial natriuretic factor ANF(1-98) is related to prognosis in severe heart failure.

Due to its longer halflife, the N-terminal of ANF prohormone, ANF(1-98), has plasma concentrations that exceed those of ANF itself by a factor of 10 or more. It is also less prone to rapid changes secondary to hemodynamic alterations. To evaluate the prognostic significance of ANF(1-98) plasma levels in severe heart failure (NYHA IV), the peptide was measured by radioimmunoassay in plasma samples from patients randomized to additional treatment with enalapril (n = 78) or placebo (n = 61) (CONSENSUS study). In the placebo group there was a positive relation between mortality after 6 months and baseline ANF(1-98) level. Because of a reduced mortality, especially among patients with high ANF(1-98) levels, there was no such relation in the patients treated with enalapril. For both groups there was a positive relationship between increase in ANF(1-98) after 6 weeks of treatment and mortality, while a decrease signaled a favorable prognosis. It is concluded that the magnitude and changes of plasma ANF(1-98) provide information on prognosis and therapeutic effects with respect to mortality in patients with severe heart failure. Plasma ANF(1-98) may serve as a useful clinical biochemical parameter in the treatment of heart failure.

Aged↗
PubMed1994

Developmental expression of poly(A) binding protein mRNAs during spermatogenesis in the mouse.

The poly(A) binding protein (PABP), a conserved protein that binds to the 3' poly(A) tail on mRNAs in eukaryotic cells, has been implicated in the regulation of mRNA stability and translation. Two PABP cDNAs with different sequences were isolated from mouse testis cDNA libraries. The predicted amino acid sequence of one, PABP1, is nearly identical (98.9%) to human liver PABP, while 80% of the amino acids of the second, PABPt, are identical to mouse and human PABPs. Northern blots reveal that there is one major PABP mRNA species in liver, muscle, kidney, and brain, two in spleen, and at least four in testis. The levels of PABP mRNA in testis are 5-10-fold higher than in these somatic tissues, but surprisingly the vast majority of all PABP mRNA size variants sediment more slowly than single ribosomes, indicating strong translational repression. Reverse transcriptase-polymerase chain reaction assays demonstrate that PABPt mRNAs are abundant only in testis. Northern blots of RNAs purified from highly enriched spermatogenic cells show that the high levels, multiple sizes of PABP mRNAs, and the PABPt mRNA are present in meiotic and early haploid spermatogenic cells, and are sharply reduced in late haploid cells. Comparison of the binding of PABP1 and PABPt to poly(A) Sepharose in vitro revealed subtle differences, even though PABPt contains substitutions for highly conserved aromatic amino acids that are thought to be necessary for binding to poly(A). The existence of two PABP isoforms in mouse spermatogenic cells could influence cytoplasmic gene expression during spermatogenesis.

Amino Acid Sequence↗
PubMed1994

Effect of enalaprilat on splanchnic vascular capacitance during acute ischemic heart failure in dogs.

This study investigates the effect of angiotensin-converting-enzyme inhibition by intravenous enalaprilat (100 micrograms/kg) on splanchnic vascular capacitance during acute left ventricular failure induced by coronary microembolization in alpha-chloralose/urethan anesthetized dogs. Changes in hepatic and splenic vascular volumes were determined from organ diameters (sonomicrometry) at 15, 30, and 45 min after enalaprilat injection. Changes in vascular capacitance were assessed from organ pressure-diameter curves obtained during transient hepatic outflow occlusion. Thirty minutes after enalaprilat, hepatic volume was increased by 52 +/- 14 ml (P < 0.01), and portal and hepatic vein pressures were decreased from 10.2 +/- 0.9 to 8.7 +/- 0.8 mmHg (P < 0.01) and from 3.9 +/- 1.6 to 3.1 +/- 0.7 mmHg (P < 0.05), respectively. Splenic volume did not change. Enalaprilat shifted the hepatic pressure-diameter curve upward, resulting in a larger hepatic volume at any given pressure. Curve intercept was increased, suggesting an increase in unstressed vascular volume. Curve slope was unchanged. In conclusion, enalaprilat increased hepatic vascular volume during acute left ventricular failure in dogs. The pressure-diameter curve shift suggests a reduction in the smooth muscle tone of hepatic capacitance vessels.

Acute Disease↗
PubMed1994

Cerebral blood flow autoregulation after moderate hypoxemia in the newborn piglet.

The isotope-labelled microsphere method was used to study blood flow autoregulation in the brainstem (BS), cerebellum (CBL), cerebrum (CBR) and choroid plexus (ChPl) in 21 newborn piglets exposed to hypoxemia and/or hypovolemia. One group of piglets (n = 7) was made hypoxemic by breathing 10% O2 for 10 min, a second group (n = 8) was studied during hypoxemia (10% O2, 10 min), followed by hypovolemia (bleeding 20% of estimated blood volume). A third group of piglets (n = 6) was made hypovolemic by bleeding 20%. Hypoxemia significantly impaired the autoregulatory capacity in CBL and CBR resulting in a pressure-passive flow pattern. Hypovolemia alone did not produce any significant cerebral vascular response in BS, CBL and CBR, not even when hypovolemia was preceded by hypoxemia, indicating a rapid restoration of the autoregulatory capacity of the cerebral vasculature after hypoxemia of moderate duration. The hypotension seen both during hypoxemia and hypovolemia was gradually compensated for and normalized within 60 min. However, animals exposed to both hypoxemia and hypovolemia were still hypotensive 60 min after the hypoxemic insult. Cardiac output (CO) was not affected by hypoxemia, but was consistently reduced in hypovolemia. We therefore speculate that in the newborn a reduced CO might be a more specific parameter for hypovolemia than a low blood pressure.

Animals↗
PubMed1994

N-terminal proatrial natriuretic factor. An independent predictor of long-term prognosis after myocardial infarction.

BACKGROUND: Atrial natriuretic factor (ANF) is a peptide hormone secreted from cardiac atria in response to increased atrial pressure. Because of a longer half-life and greater stability, the N-terminal of ANF prohormone (N-terminal proANF) may be a better integrator of atrial peptide secretion than ANF itself. After myocardial infarction, elevation of ANF and other neurohormones has been associated with a poor prognosis. However, when left ventricular ejection fraction (LVEF) and other important clinical variables are included in multivariate analysis, the independent predictive value of these neurohormones has been reduced markedly. METHODS AND RESULTS: To test the prognostic value of N-terminal proANF after myocardial infarction, its plasma concentration was measured a mean of 12 days after infarction in 246 patients in the Survival and Ventricular Enlargement (SAVE) Study. N-terminal proANF was a much stronger predictor of survival than ANF itself. Furthermore, in multivariate analysis of cardiovascular mortality and development of heart failure, N-terminal proANF in contrast to ANF and other neurohormones was still a powerful and independent predictor when the model included age, gender, prior myocardial infarction, hypertension, diabetes, use of thrombolysis, Killip class, infarct location, and LVEF. CONCLUSIONS: The measurement of N-terminal proANF supplements presently used clinical and objective assessments and provides an important independent predictor of prognosis with respect to cardiovascular mortality and development of heart failure.

Atrial Natriuretic Factor↗
PubMed1993

Validation of 1989 Tennessee birth certificates using maternal and newborn hospital records.

In 1989, the state of Tennessee adopted a new birth certificate which incorporates changes recommended by the National Center for Health Statistics in the revised US Standard Certificate of Live Birth. The data now being collected are intended to provide improved information for understanding maternal and infant health issues. To assess data quality, the authors compared information reported on the 1989 Tennessee birth certificates with the same data obtained from an ongoing case-control study in which the delivery hospital medical records of mothers and infants were reviewed by trained nurse abstractors using a structured data collection instrument. Cases (n = 1,016) were all infants born in Tennessee in 1989 with birth weights less than 1,500 g or other infants who died during the first 28 days of life. The infants were identified from linked birth-death certificate files. Control infants (n = 634) were randomly selected from the noncase population. The most reliable information obtained from birth certificates was descriptive demographic data and birth weight. The quality of information obtained from the new birth certificate checkboxes varied. Routine medical procedures were better reported on the birth certificates than relatively uncommon conditions and occurrences, even serious ones. Caution is needed in using birth certificate data for assessment of maternal medical risk factors, complications of labor and delivery, abnormal conditions of the newborn, and congenital anomalies, since sensitivity is low.

Birth Certificates↗
PubMed1993

Behavioral adaptation to human immunodeficiency virus-seropositive status in children and adolescents with hemophilia.

OBJECTIVE: To examine the behavioral adaptation to human immunodeficiency virus (HIV)-seropositive status, as defined by parental report, in children and adolescents with hemophilia. RESEARCH DESIGN: A clinical descriptive study of two groups of patients as part of a longitudinal design. SETTING: A university-based comprehensive hemophilia center and department of neurology acquired immunodeficiency syndrome dementia center. PATIENTS: Forty-six male children with hemophilia divided into two groups based on HIV-seropositive (n = 18) or -seronegative (n = 28) status. None of the patients were symptomatic for acquired immunodeficiency syndrome. SELECTION PROCEDURES: All pediatric patients with documented factor VII or IX deficiency aged between 4 and 19 years at study onset and their families were eligible to participate. All subjects were recruited without regard to human immunodeficiency virus status. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Profiles of behavioral adjustment were obtained from parents' reports on the Child Behavior Checklist for the HIV-seropositive and HIV-seronegative groups. The two groups did not differ on any of the major indexes of the Child Behavior Checklist, even after adjusting for maternal education and severity of hemophilia. There also was no difference between the groups when individual cases were examined for the number of child behavior checklist scales falling within a clinically significant range. CONCLUSIONS: The current findings fail to confirm any clear evidence of behavioral problems in an asymptomatic group of HIV-seropositive children and adolescents with hemophilia.

Adaptation, Psychological↗
PubMed1993

The T cell receptor associated CD3-epsilon protein is phosphorylated upon T cell activation in the two tyrosine residues of a conserved signal transduction motif.

Signal transduction through the T cell receptor for antigen, the TcR/CD3 complex, involves phosphorylation of tyrosine residues in the CD3-zeta chain. Since both CD3-epsilon and the zeta chain contain a tyrosine-based signaling motif, we examine phosphorylation of CD3-epsilon in human T cells. Engagement of the TcR/CD3 complex induced tyrosine phosphorylation of CD3-epsilon in vivo. Induction of CD3-epsilon phosphorylation followed similar kinetics to that of the zeta chain phosphorylation. In contrast to zeta, CD3-epsilon phosphorylation was strictly dependent upon cell surface expression of this member of the TcR/CD3 complex. Chemical and proteolytic cleavage combined with peptide-specific Western blotting established that CD3-epsilon phosphorylation occurred in the two tyrosine residues located in the signal transduction motif in the C-terminal portion of the molecule. Taken together, these data indicated that phosphorylation of CD3-epsilon by tyrosine protein kinases may serve to couple the TcR/CD3 complex to other effector molecules in the signaling cascade.

CD3 Complex↗
PubMed1993

Regional blood flow in brain and peripheral tissues during acute experimental arterial subdural bleeding.

The effects of a large intracranial arterial subdural bleeding on regional blood flow in the brain (rCBF) and in other body organs were studied, using a porcine model. The bleeding was produced by leading blood through a catheter from the abdominal aorta via an electronic drop recorder into the subdural compartment (SDC) over the left cerebral hemisphere. Pressures in the right lateral cerebral ventricle and in the cisterna magna were recorded along with 15 other vital parameters. Measurements of rCBF were carried out using radioactive microspheres 1) before the start of bleeding, 2) during the early bleeding phase, and 3) during the late bleeding phase. When the bleeding was initiated, the intracranial pressures rose within one minute to a level approximately 40 mmHg below the systemic arterial pressure, whilst the latter usually decreased 30-40 mmHg. In the subsequent early bleeding phase the cerebral perfusion pressure and the bleeding pressure fluctuated at a level of approximately 40 mmHg for several minutes. In the late bleeding phase, the perfusion pressure decreased maximally, even when a Cushing reaction was activated. During the early bleeding phase the changes in rCBF varied between the cerebral regions. However, the mean flow remained largely constant in the presence of a decreasing cerebrovascular resistance, indicating that autoregulation of CBF was intact. Concomitantly, cardiac output and heart rate decreased, whilst regional blood flow in extracerebral organs tended to increase, possibly due to an intracranial effect on the autonomic nervous system. In the late bleeding phase, rCBF was critically reduced in all regions, in spite of a marked rise in systemic arterial pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1993

Encoding ability is preserved in amnesia: evidence from a direct test of encoding.

The encoding ability of 17 amnesics of mixed aetiology and 17 matched normal controls was assessed directly using a novel procedure. On two separate occasions, subjects were shown 60 complex drawings each containing six pictures. On one occasion each drawing was shown for 6 sec, and on the other occasion it was shown for 25 sec. Immediately after presentation of each drawing subjects were asked a single unpredictable question about picture colours, location, size or semantic category. Amnesics performed normally in the 6-sec exposure condition indicating that all of the tested kinds of information were encoded at a normal rate. Performance in this condition correlated with short-term, but not long-term memory in the amnesics indicating that it depended largely on encoding and short-term memory. However, the amnesics were impaired in the 25-sec condition where performance should have depended on (long-term) memory abilities at which they were impaired. The results are inconsistent with available encoding deficit accounts of amnesia.

Adult↗
PubMed1993

Rapidly progressive acute renal failure due to acyclovir: case report and review of the literature.

Acyclovir nephrotoxicity has been described since the inception of the drug's use more than a decade ago. Acute renal failure mediated by this compound is characterized by abrupt elevations in serum creatinine and a gradual return to baseline renal function on discontinuation of the drug. Drug crystal formation in collecting tubules resulting in an intraparenchymal form of obstructive nephropathy has been suggested as the mechanism for acyclovir nephrotoxicity. The patient we present developed rapidly progressive acute renal failure with concomitant mental status changes in the setting of treatment with high-dose parenteral acyclovir. Acyclovir therapy was discontinued and an open renal biopsy was obtained to further evaluate our patient's diminishing renal function. Pathologic examination of the biopsy specimen revealed loss of proximal tubule brush border and dilated proximal and distal tubules with flattening of lining cells and focal nuclear loss. No crystals were noted. These changes were consistent with acute tubular necrosis with regeneration. Over the next 4 days our patient's renal and neurologic levels recovered to their prehospitalization statuses. It appears that our patient was affected by acyclovir-mediated nephrotoxicity that manifested on biopsy by acute tubular necrosis and the absence of crystalluria or crystal deposition. Intravenous acyclovir treatment can therefore produce rapidly progressive acute neurologic and renal toxicity that is usually reversible. The pathologic changes of acute tubular necrosis must now be included as part of the spectrum of renal damage associated with acyclovir therapy.

Acute Kidney Injury↗
PubMed1993

Comparative study of atrial peptides ANF (1-98) and ANF (99-126) as diagnostic markers of atrial distension in patients with cardiac disease.

To evaluate the possible role of atrial natriuretic peptides ANF (1-98) and ANF (99-126) as diagnostic parameters of atrial distension, measurements of peptide levels were performed in 47 patients with chronic ischemic and/or left sided valvular heart disease. Plasma samples were drawn from the pulmonary artery (PA) and superior vena cava (SVC) during diagnostic right heart catheterization. Forty of the patients also underwent left heart haemodynamic measurements, and in 28 patients two dimensional echocardiography with determination of left atrial diameter was performed. Enhanced plasma concentrations of both peptides were observed with increasing severity of heart failure assessed by the NYHA classification. Mean plasma levels of both peptides were closely correlated to mean pulmonary artery pressure (ANF (1-98): n = 47, r = 0.69 (SVC)/r = 0.72 (PA), p < 0.0001; ANF (99-126): n = 46, r = 0.75 (SVC)/r = 0.68 (PA), p < 0.0001) and mean pulmonary capillary wedge pressure (ANF (1-98): n = 47, r = 0.69 (SVC)/r = 0.72 (PA), p < 0.0001; ANF (99-126): n = 46, r = 0.70 (SVC)/r = 0.64 (PA), p < 0.0001). Positive correlations were also obtained between peptide levels and mean right atrial pressure and left ventricular end-diastolic pressure. When patients with high right atrial pressures (n = 2) were excluded from analysis, a significant correlation was found between peptide levels and echocardiography assessed left atrial diameter. The present study demonstrates the close correlation between concentrations of both atrial peptides and cardiopulmonary haemodynamics in patients with chronic heart disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Imagery effects on the performance of skilled and novice soccer players.

The purpose of this study was to investigate the effect of an imagery training programme on the performance of a soccer task by skilled and novice players. An initial assessment of performance on the soccer task was undertaken, and then 22 skilled and 22 novice players were equally and randomly assigned to either a control or an experimental group. The experimental group was given an imagery training programme consisting of both visual and kinaesthetic imagery, and in which both internal and external imagery perspectives were included. The programme lasted 6 weeks, with the subjects attending bi-weekly sessions of approximately 15 min each. The control group developed a competitive strategy that was totally unrelated to the performance task. Similar to the experimental group, the controls did this over a 6-week period, attending bi-weekly sessions of 15 min duration. Two performance measures were recorded--response time (i.e. the time to complete the soccer task) and performance accuracy (i.e. errors in performing the soccer task recorded in the form of time penalties). Performance on the post-test as measured by response time revealed a significant improvement for both the skilled and novice players in the imagery group. The control group failed to show any such improvement. No effects were found for performance accuracy.

Adolescent↗
PubMed1993

Atrial peptides, ANP(1-98) and ANP(99-126) in health and disease in an elderly population.

Circulating immunoreactive atrial natriuretic peptide, IrANP(99-126) and the N-terminal fragment of the prohormone, IrANP(1-98) were measured in two population samples from the general population of Gothenburg, Sweden. A group of 85-year olds (974 subjects) and a group of 40-year olds (191 subjects) were investigated in respect of cardiovascular, renal and metabolic disease. IrANP(99-126) and IrANP(1-98) were significantly higher in the 85-year olds compared to the 40-year olds, and were significantly increased in subjects with congestive heart failure, ischaemic heart disease, atrial fibrillation and renal dysfunction but not in subjects with hypertension. Eighty-five-year-old subjects who were on treatment with digitalis, beta-adrenergic-blockers, nitrates and diuretics had significantly increased IrANP(99-126) and IrANP(1-98). In multivariate analysis IrANP(99-126) concentrations were predictive for congestive heart failure, ischaemic heart disease, atrial fibrillation and treatment with beta-blockers and anti-depressant drugs. IrANP(1-98) was predictive for congestive heart failure, ischaemic heart disease, atrial fibrillation, diabetes mellitus, renal failure and drug treatment with beta-blockers and neuroleptics. We conclude that measurements of circulating concentrations of IrANP(99-126) and/or IrANP(1-98) may add valuable information in the diagnosis of congestive heart failure and ischaemic heart disease in an elderly population. It remains to be determined whether routine measurements of circulating IrANP (99-126) and IrANP(1-98) may be of value in predicting current cardiovascular disease for the individual patient.

Adult↗