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Biomedical subjects

M Hart

Publications and source records attributed to M Hart.

At least 91 records · Page 5Linked to original sources
PubMed1988

Idiopathic dilated cardiomyopathy. Role of programmed electrical stimulation and Holter monitoring in predicting those at risk of sudden death.

The prognostic role of programmed electrical stimulation and Holter monitoring was evaluated in 21 patients with idiopathic dilated cardiomyopathy who had no prior history of ventricular tachyarrhythmias. During a mean follow-up period of 23 months, sudden death or ventricular fibrillation occurred in four (20 percent). One patient died of complications of sepsis, and one underwent cardiac transplantation. Programmed electrical stimulation (PES) resulted in five or more beats of induced ventricular tachycardia in seven patients (33 percent), but was a poor predictor of sudden death (sensitivity = 20 percent). Thirteen patients (62 percent) had complex ventricular ectopy (Lown class 4A or 4B) by ambulatory monitoring. This was a sensitive (80 percent) but not specific (31 percent) marker for sudden death. The predictive value of a negative Holter monitor study was high (80 percent) for identifying those at low risk of sudden death. The results of this prospective study suggest that programmed ventricular stimulation and routine ambulatory monitoring are poor predictors of sudden death in this population.

Adult↗
PubMed1987

Multiple congenital anomalies syndrome with myopathy in chromosome 16 abnormality.

An abnormality of chromosome 16 in an eight year-old male was associated with a multiple congenital anomalies syndrome characterized by myopathy, cataracts, blepharophimosis, microcephaly, failure to grow, profound mental retardation, moderate sensorineural hearing loss, grand mal seizures, bilateral inguinal hernia, and thoracolumbar kyphoscoliosis. Magnetic resonance imaging of the head demonstrated absence of the corpus callosum and extensive loss of brain parenchyma in the occipital regions. Chromosome analysis from peripheral blood of the patient showed a recombinant chromosome 16 [46, XY, rec (16), dup (p13.1----p13.3) del (q22----q24)]. The mother had a pericentric inversion of chromosome 16 [46, XX, inv(16) (p13.1;q22)]. Independent recombinant DNA studies have shown that the breakpoints of these chromosomal rearrangements flank the alpha-globin gene cluster locus.

Abnormalities, Multiple↗
PubMed1987

Expression of variant von Willebrand factor (vWF) cDNA in heterologous cells: requirement of the pro-polypeptide in vWF multimer formation.

Von Willebrand factor (vWF) is a multimeric plasma glycoprotein synthesized by vascular endothelial cells as a pre-pro-polypeptide with a highly repetitive domain structure, symbolized by the formula: (H)-D1-D2-D'-D3-A1-A2-A3-D4-B1-B2-B3-C1-C2-(OH) A heterologous expression system for the synthesis of recombinant vWF protein was developed, consisting of a monkey kidney cell line (COS-1), transfected with full-length vWF cDNA. This system was shown to mimic the constitutive secretory pathway of vWF in endothelial cells, since dimerization and multimerization occur similarly. To determine whether the pro-polypeptide, composed of the domains D1 and D2, is involved in vWF multimerization, a vWF cDNA was constructed that lacked the coding sequence for the pro-polypeptide. The mutant vWF protein, expressed by COS-1 cells transfected with this cDNA, did not assemble beyond the dimer stage. From this observation, we conclude that (i) dimerization does not involve the pro-polypeptide of pro-vWF and (ii) the presence of the pro-polypeptide, as part of pro-vWF, is obligatory for multimerization. It is argued that the interactions, required for interchain binding, are mediated by the D domains.

Animals↗
PubMed1986

Full-length von Willebrand factor (vWF) cDNA encodes a highly repetitive protein considerably larger than the mature vWF subunit.

Full-length human von Willebrand factor (vWF) cDNA was assembled from partial, overlapping vWF cDNAs. This cDNA construct includes a coding sequence of 8439 nucleotides which encode a single-chain precursor of 2813 amino-acid residues, representing a putative signal peptide, a prosequence and mature vWF of 22, 741 and 2050 amino acids, respectively. This represents the longest coding sequence determined to date. In-vitro expression of full-length vWF cDNA revealed the synthesis of a polypeptide with a mol. wt corresponding with that of the unglycosylated precursor. The precursor is a highly repetitive protein which consists of two duplicated (B, C), a triplicated (A), a quadruplicated (D) and a partly duplicated domain (D'), in the following order: H-D1-D2-D'-D3-A1-A2-A3-D4-B1-B2-C1-C2-OH. Both the prosequence, composed of two D domains (D1, D2), and mature vWF harbor an arg-gly-asp ('R-G-D') sequence which has been implicated in cell-attachment functions. It is argued that the pro-sequence is equivalent to von Willebrand Antigen II (vW AgII).

Amino Acid Sequence↗
PubMed1985

Dietary sodium and arterial blood pressure: evidence against genetic susceptibility.

Thirty five subjects with both parents in the top third of their age specific blood pressure distributions and 31 subjects with both parents in the bottom third of their blood pressure distributions restricted their intake of sodium for eight weeks while taking part in a double blind, randomised crossover trial of supplements of sodium and placebo. A comparison of two periods of four weeks at different intakes of sodium showed no differences in blood pressure in either the groups as a whole or the subgroups who complied best with the diet and tablets. In the compliant subgroups mean urinary sodium excretions were above 120 mmol(mEq) and below 50 mmol/day. The study provides evidence against the hypothesis that people with a family history of high blood pressure are more susceptible in their blood pressure response to dietary sodium.

Adult↗
PubMed1985

Changing aspects of radiation enteropathy.

Fifty-two patients with radiation enteropathy secondary to radiation for abdominal or pelvic malignant neoplasms are described. This series (1977 to 1984) is compared with a series of 50 patients from the same institution over an earlier period (1961 to 1977). Intestinal obstruction was the principal complication in both series; 96% of the patients underwent either intestinal resection or anastomotic bypass of the affected segment. Changes that have occurred since the last report are as follows: changes in source of radiation energy (linear accelerator); less evidence of mucosal damage; increased serosal reaction ("serosal peel"); and increased use of elemental diets, parenteral nutrition, and long intestinal tubes in surgical management. Since postoperative radiation injury occurs most frequently in the pelvis, new developments for the exclusion of small bowel from the pelvis during radiation are reviewed. Changes in fractionation of radiation dosage should also be considered in patients with enteric symptoms during radiation therapy.

Abdominal Neoplasms↗
PubMed1985

Primary intracranial rhabdomyosarcoma.

Primary intracranial rhabdomyosarcoma is rare. Twenty-one cases with dismal outcomes have been reported. We add five children with this disease treated between 1977 and 1982. Their therapy consisted of surgical resection, craniospinal irradiation, and intravenous-intrathecal chemotherapy. Two children have recovered, 21 and 67 months after diagnosis; the last is the longest survival reported in the literature. Two succumbed to tumor recurrence, and one died due to pulmonary embolism. The posterior fossa was invariably a site of tumor at presentation. Diagnosis with light microscopy can be elusive; electron microscopic and immunohistochemical evaluation are necessary to confirm the pathological condition. This is essential so that early, aggressive therapy can be instituted. These diagnostic and therapeutic techniques have led to a reevaluation of this malignancy and its prognosis.

Adolescent↗
PubMed1983

Dietary sodium restriction for mild hypertension in general practice.

Eighteen patients with stable mild hypertension (mean blood pressure 144/93 mm Hg) restricted their sodium intake for eight weeks while taking part in a double blind randomised crossover trial of slow sodium and placebo tablets. Mean 24 hour urinary sodium excretion was 143 mmol(mEq) during the period on slow sodium and 87 mmol during the period on placebo. Five patients were unable to reduce their sodium intake below 120 mmol, but the others had a mean 24 hour urinary sodium excretion of 59 mmol during the period on placebo. There was no significant difference in blood pressure between the slow sodium and placebo treatment periods, although the study had a power of 99% to detect a difference of 5 mm Hg in mean arterial pressure between the two periods. Moderate dietary sodium restriction does not lower blood pressure in patients with this degree of hypertension.

Adult↗
PubMed1983

Inherited ophthalmoplegia with intestinal pseudo-obstruction.

A new inherited neuromuscular disease was identified in 4 patients (1 male, 3 females), offspring of consanguineous marriages, belonging to the same kindred. The proband was a 24-year-old female with history of ptosis and ophthalmoplegia since childhood and progressive intestinal pseudo-obstruction for the last 4 years of her life. A sural nerve biopsy showed axonal and demyelinating neuropathy. Muscle biopsies of pectoral and gastrocnemius revealed myopathic alterations with marked variation in muscle fiber size, atrophy of both fiber types and normal mitochondria. An upper gastrointestinal study showed barium in the stomach after 8 h and jejunal diverticula. Tests for absorption of fat, protein, carbohydrate, folic acid and vitamin B12 were normal. Serum levels of vitamin A and lipoproteins were also normal. The patient underwent partial gastrectomy and gastrojejunostomy. Postoperatively, she developed severe pancreatitis, sepsis, peritonitis and expired. Tissue samples from the proband and from her brother, revealed normal mucosa, but degeneration of smooth muscle of the stomach and small intestine. The myenteric plexus and vagus nerves were normal. The biochemical studies of contractile proteins (myosin, actin, tropomyosin) in the fresh and cultured smooth muscle cells of the proband obtained at the time of gastrectomy showed a 50-75% decrease in the synthesis of different contractile proteins. Turnover of contractile proteins and synthesis and turnover of collagen showed normal values. The reduction in synthesis of contractile proteins may account for the weak peristalsis and be a factor in the pathogenesis of the intestinal pseudo-obstruction.

Adult↗
PubMed1982

Food behavior of elementary school students after receiving nutrition education.

A nine-week nutrition education program for kindergarten through sixth grade was implemented and its influence on children's food behavior assessed using a pretest/post-test design involving children who were and were not exposed to the program. The food behavior response was mixed. Consumption of some food items, at post-test time, was higher among pupils exposed to the program, but that of other items was lower, and consumption of some items was unaffected. Responses to questionnaires by parents indicated that they perceived a favorable effect of the nutrition education program on their children's food behavior.

Child↗