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Biomedical subjects

M Skelton

Publications and source records attributed to M Skelton.

15 recordsLinked to original sources
PubMed2001

Is thrombophilia a factor in the development of hemiplegic cerebral palsy?

A population-based study of children with hemiplegic cerebral palsy (CP) was performed to investigate whether thrombophilic tendencies are implicated in the aetiology of the condition. Thirty-eight children (23 males, 15 females; mean age 8.7 years, SD 4.1 years) with hemiplegic CP were ascertained. Twenty-seven children(18 males, nine females; mean age 8.4 years, SD 4.3) gave consent for inclusion. The non-study group comprised five males and six females; mean age 9.4 years, SD 4.1. In six children, seven thrombophilic 'abnormalities' were identified. Five of these abnormalities were of an equivocal nature and probably did not represent true clinical thrombophilia; reasons for this interpretation are discussed. Contrary to other published non-population-based studies, we have not shown an association between thrombophilia and hemiplegic CP. More studies, including maternal studies, are required to explore this complex subject further.

Atrophy↗
PubMed2000

Transfusion-transmissible virus and hepatocellular carcinoma: a case-control study.

Although transfusion-transmissible virus (TTV) is often present in the serum of patients with acute and chronic non-A-C liver diseases, its hepatotropism, pathogenicity to the liver and hepatocarcinogenicity have not been proven. We used a case-control format to compare the prevalence of TTV infection among 148 southern African Blacks with hepatocellular carcinoma and 148 matched hospital-based controls, and to test for possible interactive effects between this virus and hepatitis B virus (HBV) and hepatitis C virus (HCV) in the development of the tumour. We also determined the prevalence of TTV in 988 blood donors in Gauteng province of South Africa. The presence of TTV DNA in serum samples was detected by using the polymerase chain reaction, Southern hybridization and nucleotide sequencing. Individuals infected with TTV did not have an increased risk of developing hepatocellular carcinoma (relative risk 1.1; 95% confidence limits 0.5-2.4). Moreover, co-infection with TTV did not further increase the risk of tumour development in patients chronically infected with HBV and/or HCV. TTV was present in the serum of 2.2% of blood donors: 4.0% in Black and 1.5% in White donors. We conclude that TTV is unrelated to the development of hepatocellular carcinoma in Black Africans.

Adolescent↗
PubMed1998

Non-specificity of messenger RNA of alpha-fetoprotein in peripheral blood in detecting early spread of hepatocellular carcinoma in black Africans.

Awareness of early spread of hepatocellular carcinoma is crucial in selecting patients for surgical intervention. Alpha-fetoprotein is widely used as a serum marker for hepatocellular carcinoma. Our aim was to evaluate the specificity of alpha-fetoprotein-mRNA transcription in cells in the peripheral blood for diagnosing early spread of hepatocellular carcinoma in black Africans. Alpha-fetoprotein-, albumin- and prothrombin-mRNA were detected in peripheral blood mononuclear cells by reverse transcription-polymerase chain reaction. Alpha-fetoprotein-mRNA was shown in peripheral blood mononuclear cells in 53% (35/66) of patients with hepatocellular carcinoma, but also in 45% (10/22) of healthy blacks, 64% (14/22) of black patients with acute hepatitis, 55% (11/20) of those with chronic hepatitis or cirrhosis and 75% (9/12) of those with hepatic metastases (from a number of primary sites). Specificity of albumin- and prothrombin-mRNA was better than that of alpha-fetoprotein-mRNA, although the sensitivity was reduced. The corresponding prevalence of albumin-mRNA for each group of patients or controls was 30% (20/66), 9% (2/22), 41% (9/22), 10% (2/20), and 17% (2/12), respectively, and for prothrombin-mRNA 27% (18/66), 4.5% (1/22), 27% (6/22), 20% (4/20) and 17% (2/12), respectively. We conclude that the non-specificity of alpha-fetoprotein-mRNA transcription in peripheral blood in recognizing malignant hepatocytes in the circulation severely limits its usefulness in diagnosing the early spread of hepatocellular carcinoma in black Africans.

Adolescent↗
PubMed1997

Does hepatitis GB virus-C infection cause hepatocellular carcinoma in black Africans?

The newly cloned and characterized hepatitis GB virus-C (HGBV-C), which is the same virus as the independently discovered hepatitis G virus, has a global distribution, is transmitted parenterally, and causes chronic viremia. The pathological consequences of infection with HGBV-C are uncertain, and its hepatocarcinogenic potential is unknown. We used a case-control format to compare the prevalence of HGBV-C infection in 167 southern African blacks with hepatocellular carcinoma (HCC) and 167 race-, age-, and sex-matched hospital-based control subjects, and to test for possible interactive effects between this virus and hepatitis B and C viruses in the development of the tumor. The presence of HGBV-C ribonucleic acid was detected in serum samples by reverse transcription, amplification of the resulting complementary deoxyribonucleic acid by the polymerase chain reaction (PCR), and Southern hybridization using a probe from the NS3/helicase region of the genome. Serum samples were also tested for the presence of hepatitis B virus surface antigen, antibodies to hepatitis C virus, and hepatitis C virus ribonucleic acid. Individuals infected with HGBV-C did not have an increased relative risk of developing HCC (relative risk 0.9; 95% confidence limits 0.5, 1.7). Moreover, co-infection with HGBV-C did not further increase the risk of tumor development in patients who were chronically infected with hepatitis B and/or C viruses. HGBV-C is unrelated to hepatocellular carcinoma development in black Africans.

Black or African American↗
PubMed1995

Secondary tumours following etoposide containing therapy for germ cell cancer.

BACKGROUND: Reports have implied etoposide as the cause of secondary leukaemia in patients treated for germ cell cancer. PATIENTS AND METHODS: Between 1979 and 1992, 679 male patients with germ cell cancer received etoposide containing chemotherapy. RESULTS: Six of 679 patients developed acute myeloid leukaemia (relative risk 150; CI: 55-326). None of these patients had a primary mediastinal germ cell tumour and only 1 patient received previous radiotherapy. The median interval between the onset of cytotoxic treatment and the development of leukaemia was 27 months. The FAB M4 morphology was seen in 4 of 6 cases. CONCLUSION: The benefit of etoposide containing protocols outweigh the risk of leukaemia in patients with intermediate or high risk disease, however in patients with good risk disease non-etoposide containing protocols should be explored.

Acute Disease↗
PubMed1992

Control of the cardiovascular system of Aplysia by identified neurons.

The neural network that controls the cardiovascular system of Aplysia adapts cardiovascular function to a variety of different physiological and behavioral situations. It (1) coordinates the cardiovascular system with the renal and respiratory systems; (2) modifies both systemic and regional blood flow during food-elicited arousal and feeding; and (3) changes the tension of longitudinal vascular muscle to adapt the arterial tree to changes in body shape. Indirect evidence suggests that the cardiovascular control circuit may also play a role in maintaining homeostasis during egg laying. Several putative neurotransmitters, including acetylcholine, serotonin, R15 alpha 1 and R15 alpha 2 peptides, have been localized to identified neurons in this circuit.

Animals↗
PubMed1987

Atriopeptin III alters renal medullary hemodynamics and the pressure-diuresis response in rats.

The effects of atriopeptin III on the renal response to changes in renal perfusion pressure (RPP) were examined in uninephrectomized and adrenalectomized rats. Neural influences on the kidney were eliminated by renal denervation. Plasma levels of antidiuretic hormone (ADH), angiotensin II, aldosterone, corticosterone, and norepinephrine were controlled by intravenous infusion. Infusion of atriopeptin III at a dose of 30 or 100 ng X kg-1 X min-1 increased plasma levels of atrial natriuretic peptide from 101 +/- 8 pg/ml to 424 +/- 16 and 2,553 +/- 308 pg/ml, respectively. In control rats, increasing RPP in two steps from 100 to 125 to 150 mmHg produced sixfold increases in sodium and water excretion. The slopes of the relationships between fractional sodium and water excretion and RPP were enhanced by approximately 10, 20, and 40% in the rats infused with the 30, 100, and 500 ng X kg-1 X min-1 dose of atriopeptin III. Renal blood flow and glomerular filtration rate were not significantly different in vehicle- and atriopeptin III-infused rats at any RPP studied. Papillary blood flow measured with a laser-Doppler flowmeter increased 15% within the first 5 min of infusion of atriopeptin III at a dose of 100 ng X kg-1 X min-1. Cortical blood flow was not significantly altered. The rise in papillary blood flow during atriopeptin III infusion, however, may be a consequence and not the cause of the natriuresis and diuresis, since urine flow increased before significant changes in papillary blood flow were detected. These studies suggest that atrial natriuretic factor could influence the long-term control of arterial pressure by altering renal medullary hemodynamics and promoting the elimination of sodium and water. The plasma levels of atrial natriuretic peptide needed to alter the pressure-natriuresis relationship, however, may exceed levels that can be attained in vivo with endogenous release.

Animals↗
PubMed1986

Vasopressin reduces cardiac function and augments cardiopulmonary baroreflex resistance increases in man.

We examined the effects of physiologic infusions of arginine vasopressin (AVP) on cardiovascular hemodynamics and on reflex responses initiated by decreasing cardiopulmonary baroreceptor stimulation (with lower body negative pressure) in 10 healthy, captopril-pretreated young men (19-27 yr). Their responses were compared with those of four volunteers given isosmotic infusion. Heart rate, stroke volume, blood pressure, and forearm blood flow were measured by electrocardiography, impedance cardiography, radial artery cannulation, and strain gauge plethysmography. Two 55-min infusions of AVP at rates of 0.15 and 0.40 ng/kg per min increased average plasma concentrations from control levels of 5 pg/ml to 18 and 36 pg/ml, respectively. These infusions resulted in progressive reductions of heart rate and cardiac output and increases of forearm and total peripheral resistance. Blood pressure increases were significant only during the larger AVP infusion rate. Lower body negative pressure provoked reflex increases of total peripheral resistance. These increases were enhanced 60% during AVP infusion compared with increases during control (pre-AVP). Baseline measurements and reflex responses were unchanged by isosmotic infusions. These results demonstrate that AVP has profound effects on cardiovascular function and augments cardiopulmonary baroreflex-mediated increases of peripheral resistance in man.

Adolescent↗
PubMed1986

Elevated plasma vasopressin (AVP) levels during resection of pheochromocytomas.

During the evaluation of epidural blockade with light general anesthesia for pheochromocytoma resection, increases in plasma arginine vasopressin (AVP) concentrations were noted. We measured AVP levels in conjunction with plasma catecholamines during perioperative maneuvers in eight consecutive patients undergoing resection of pheochromocytomas. Hormonal responses (mean +/- SE) for preoperative baseline and peak values during tumor manipulation were as follows: AVP, 5 microgram/ml or picogram/ml (+/- 1.7) to a peak of 129 pg/ml (+/- 44) pg/ml; norepinephrine, 5,834 pg/ml (+/- 2,564) to 72,422 (+/- 31,433) pg/ml; epinephrine, 1,033 pg/ml (+/- 405) to 56,444 (+/- 23,542) pg/ml; and dopamine, 165 pg/ml (+/- 35) to 4,231 (+/- 1,318) pg/ml. Maximal AVP values occurred with tumor manipulation and remained elevated for 24 hours postoperatively. Neither epidural placement, induction of anesthesia, nor epidural narcotics used for postoperative pain control had any effect on AVP or catecholamine levels. These extraordinarily high concentrations of plasma AVP found during tumor manipulation may contribute to hemodynamic lability and fluid problems in patients undergoing surgery for the treatment of pheochromocytoma.

Adolescent↗
PubMed1985

Control of ACTH and vasopressin in neurohypophysectomized conscious dogs.

Adrenocorticotropin (ACTH), cortisol, and vasopressin responses to clamped decreases in blood pressure (MAP) and to ovine corticotropin-releasing factor (CRF) infusion (20 ng X kg-1 X min-1) in intact and neurohypophysectomized (NHX) conscious dogs were examined. Mean arterial blood pressure was decreased 28 mmHg by a controlled infusion of sodium nitroprusside. Hypotension induced large increases in ACTH (peak 164 +/- 25 pg/ml), cortisol (peak 12.5 +/- 2.5 micrograms/dl), and vasopressin (peak 221 +/- 64 pg/ml) in intact (n = 7) dogs. NHX (n = 7) significantly attenuated these responses to hypotension. CRF infusion induced increases in ACTH similar in intact (n = 4) and NHX (n = 4) dogs. However, cortisol responses were significantly attenuated by NHX. Interestingly, CRF infusion induced small but significant increases in vasopressin from 3.0 +/- 1.1 to 8.1 +/- 2.0 pg/ml. We conclude that NHX attenuates ACTH and vasopressin responses to hypotension and cortisol responses to CRF-induced increases in ACTH. CRF seems to stimulate vasopressin release.

Adrenocorticotropic Hormone↗
PubMed1984

Prostaglandin-vasopressin interactions on the renal handling of calcium and magnesium.

The role of prostaglandins in the regulation of sodium and water excretion has been widely studied, but little is known about the influence of prostaglandins (PGs) on the tubular handling of calcium, magnesium or phosphorus. Recent observations have suggested that PGE2 and vasopressin may interact and influence reabsorption of calcium and phosphorus in the cortical collecting duct. The present study investigated the effect of meclofenamate (2 mg/kg), and inhibitor of PG synthesis, on the excretion of calcium, magnesium and phosphorus. Experiments were performed in antidiuretic and water diuretic rats to examine potential PG-vasopressin interactions on the reabsorption of these ions by renal tubules. In antidiuretic rats given meclofenamate, urine osmolality increased whereas urine flow and the fractional excretion of water, urea, sodium, calcium and magnesium decreased by 30 to 50%. In water diuretic animals, urine osmolality and urea excretion were unaltered after meclofenamate administration. Fractional excretion of sodium, water, calcium and magnesium declined approximately 50% in water diuretic rats given meclofenamate. Urinary excretion of PGE2 was not significantly different in water diuretic and antidiuretic rats averaging 262 +/- 78 vs. 167 +/- 35 pg/min, respectively. Meclofenamate significantly reduced urinary excretion of PGE2 in both groups. The results indicate that renal PGs modulate renal tubular reabsorption of calcium and magnesium, as well as sodium and water.

Absorption↗
PubMed1973

Psychological stress in wives of patients with myocardial infarction.

In a study of the psychological consequences of myocardial infarction on 65 wives of husbands admitted to a coronary care unit feelings of loss, depression, and guilt were common at the time of infarction. Many wives (38%) found the period of convalescence after discharge very stressful, attributing this to fears of a recurrent infarct and marital tension owing to their husbands' increased irritability and dependency. These anxieties and tensions gradually diminished and at one year after the initial illness only eight wives whose husbands had made a good physical recovery still showed considerable psychological disturbance. It is suggested that unnecessary emotional distress, particularly in the initial period after discharge from hospital, can be alleviated by increased help and support from the hospital and family doctor.

Adult↗