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Biomedical subjects

M L Clark

Publications and source records attributed to M L Clark.

At least 91 records · Page 5Linked to original sources
PubMed1985

Relative nutritional value of whole protein, hydrolysed protein and free amino acids in man.

To compare their effects on nitrogen balance, diets containing either lactalbumin whole protein, its peptide-rich enzymic hydrolysate or an equivalent mixture of free amino acids as the sole source of dietary nitrogen were fed to two healthy subjects, each studied for 38 days on two separate occasions. The nitrogen intake (47 mg/kg body wt/day) induced a state of negative nitrogen balance, stimulating nitrogen conservation. Net daily nitrogen balance (mean +/- SD) in subject 1 was -0.23 +/- 0.72 g (amino acids) vs + 0.05 +/- 0.52 g (protein) and -0.21 +/- 0.58 g (amino acids) vs -0.05 +/- 0.57 g (hydrolysate), and in subject 2, -0.19 +/- 0.60 g (amino acids) vs -0.16 +/- 0.51 g (protein) and -0.42 +/- 0.35 g (amino acids) vs -0.62 +/- 0.34 g (hydrolysate). Analysis of these results by the cumulative sum technique showed no significant differences in the effect of the three nitrogen sources on nitrogen balance. This study indicates that there is no nutritional evidence to support the current practice of prescribing expensive enteral diets containing peptides or amino acids rather than the much cheaper whole protein to patients with normal gastrointestinal function.

Amino Acids↗
PubMed1985

The comparative evaluation of California's multipurpose senior services project.

The Multipurpose Senior Services Project implemented a case management model of service coordination for aged Medicaid recipients at eight sites throughout California. The answers to the evaluation questions--"What works?", "For whom?", and "At what cost?" provide policy direction for long-term care programs. The research and demonstration Project ended in June 1983 and an on-going Program began in July 1983. Dynamic modeling of the outcomes of MSSP and of a comparison group served by the existing service system showed that MSSP increased longevity, decreased nursing home days, and decreased hospital days (in 1982); these results were most efficient for the frailest clients. This group had the greatest savings on public service dollars, with the Federal government the beneficiary through lower than expected Medicare expenditures. In-home supportive services proved to be the most productive non-medical service in both systems, but was more productive through MSSP. The evaluation methodology provides a multivariate frailty measure based on expected nursing home entry that can be used to identify those individuals for whom case management is most likely to have efficient outcomes.

Aged↗
PubMed1985

The behavioral and linguistic interactions of specifically language-delayed and normal boys with their mothers.

3 studies were based on subgroups selected from larger pools of either normal children or children with delays in the expression and/or comprehension of language but normal nonverbal abilities. In Study 1, younger (28-50 months) and older (51-68 months) normal (N = 27) and language-delayed (N = 33) boys were observed interacting with their mothers in free play and structured task situations. Although language-delayed children initiated fewer interactions, their responsiveness to maternal interactions, questions, and commands did not differ from that of normal children. Mothers questioned language-delayed children less frequently during tasks but did not differ from mothers of normal children on other measures of interaction, responsiveness, control, or reward strategies. In Study 2, the complexity of maternal speech directed to normal (N = 11) and expressively delayed (N = 11) boys who were matched on the basis of comprehensive skills did not differ. Maternal speech to boys with delays in both language expression and comprehension (N = 11) was significantly less complex. In Study 3, the discrepancy between the speech complexity of mothers and that of their language-delayed children (N = 47) was greatest in younger children with greater expression and comprehension delays, who initiated fewer interactions and proved less responsive to maternal interactions and questions.

Child↗
PubMed1985

General and specific self-esteem in late adolescent students: race x gender x SES effects.

This study assessed the effects of gender, race, and social class on the general and area-specific self-esteem of high school students. One hundred and ninety-five high school students served as subjects in a 2 (gender: male, female) X 2 (race: black, white) X 3 (social class: low, middle and high) factorial design. The Rosenberg General Self-Esteem, the Piers-Harris Children's Self-Concept, and the Brookover Self-Concept of Ability and School Achievement scales were the measures of either general or specific self-esteem. Females, whites, and lower social class adolescents were consistently lower in their self-esteem scores than were males, blacks, and upper social class teenagers, respectively. White females were found to be lower in general and happiness self-esteem than all other gender by race subgroups. High SES white students were lower on the happiness and behavior self-esteem measures than black students and white middle-class students. Black males and white females were less confident in their school ability than were black females and white males.

Achievement↗
PubMed1984

Identification of two intestinal vitamin D-dependent calcium-binding proteins in the X-linked hypophosphataemic mouse.

Two vitamin D-dependent calcium binding proteins (CaBP) of molecular weight approximately 10,000 and 30,000 daltons have been identified in the intestinal mucosal cell cytosol of genetically hypophosphataemic (Hyp) male mice and their normal littermates. Similar amounts of vitamin D-dependent CaBP were found in the two groups of animals. The possible significance of this observation is discussed.

Animals↗
PubMed1984

Jejunal motility in patients with functional abdominal pain.

A radiotelemetric system using dual pressure pills was used to record the jejunal motility in man. Prolonged recordings were made under relatively physiological conditions. Six patients with functional abdominal pain and six age/sex matched normal subjects were studied. Motility patterns varied markedly both within and between subjects. No differences were detected between the two groups. In particular, the occurrence of characteristic pain in the patients bore no relation to the recorded motor activity. The wide range of jejunal motility patterns in normal subjects needs to be appreciated before conclusions can be drawn about possible abnormalities in gut diseases or disorders.

Adult↗
PubMed1983

Preschool teachers' ratings of behavioral problems: observational, sociometric, and social-cognitive correlates.

Behar and Stringfield (1974) have suggested that the Preschool Behavior Questionnaire (PBQ) is a reliable index of young children's social competence. However, there are few extant data in which teacher ratings of children on the PBQ have been correlated with independent assessments of social competence. In this study PBQ ratings of 123 preschoolers were correlated with observations of in-class social and cognitive play behaviors, sociometric status, and social problem-solving skills. Analyses indicated that children rated highly on the PBQ's Anxious-Fearful, Hostile-Aggressive, and Hyperactive-Distractible factors (a) displayed less mature and more aggressive in-class behaviors, (b) were less popular among their peers, and (c) were more likely to suggest negative affect strategies on the social problem-solving measure. Thus, the PBQ appears to be a useful instrument for identifying children with social problems.

Affective Symptoms↗
PubMed1983

Treatment of advanced malignant melanoma with high-dose melphalan and autologous bone marrow transplantation.

Twenty-eight patients with advanced life-threatening metastatic malignant melanoma were treated with high dose (140-260 mgm-2) intravenous melphalan and autologous bone marrow. Cyclophosphamide "priming" 300 mgm-2 i.v. was given to 19 patients one week previously and this resulted in clinical but not histological evidence of amelioration of gastrointestinal toxicity. In 11 patients (43%) there was evidence of tumour response to treatment and in 2 patients complete remissions were observed. However in most patients, responses were short-lived and no patient lived longer than 17 months from start of treatment or 24 months from first recorded evidence of distant metastatic disease.

Adult↗
PubMed1983

Lung changes in rats inhaling volcanic ash for one year.

Rats were exposed to 5 mg/m3 or 50 mg/m3 (respirable aerosol concentration) volcanic ash, or to 50 mg/m3 quartz, 6 h/day, 5 days/wk, for as long as 12 months. Subgroups of rats were killed at 4-month intervals to determine lesion development as a function of dose and cumulative exposure. Treatment-related lung changes comprised alveolar macrophage accumulation, interstitial reaction, peribronchiolar lymphoid hyperplasia, lymph node hyperplasia, and--in the 50 . mg/m3 ash-exposed and quartz-exposed rats--alveolar proteinosis. Some of the changes did not increase appreciably after 8 months of exposure, whereas others continued to increase as a function of cumulative exposure. Generally, there were distinct dose-response and agent-response relationships. These trends were also observed in lung weights, respiratory rates, and volumes of mediastinal lymph nodes. Like the histologic changes, the effects on these ancillary parameters also increased in the following order: sham-exposed control group, 5 mg/m3 and 50 mg/m3 ash-exposed groups, and quartz-exposed positive control group.

Air Pollutants↗
PubMed1982

Effects of concentration on in vivo absorption of a peptide containing protein hydrolysate.

Amino acid absorption from a peptide-containing protein hydrolysate and an equivalent amino acid mixture over a range of concentrations of the two--such as is thought to be found in the normal intestine after a meal--has been studied using a jejunal perfusion technique in man. The relative rates of amino acid absorption from the protein hydrolysate and amino acid mixture varied markedly with concentration, demonstrating that the global hypothesis that peptides confer an advantage in amino acid absorption in vivo is too simple. There is a highly significant correlation between amino acid absorption and the concentrations of amino acid in the perfusate, whether this contained amino acid or protein hydrolysate, suggesting that, under these experimental conditions at least, the presence of distinct amino acid and peptide transport systems is relatively unimportant. Doubt is thus cast upon suggestions derived from previous intestinal perfusion experiments that intact peptide transport may be nutritionally significant in man.

Adult↗
PubMed1982

Liver disease after bone marrow transplantation.

Liver dysfunction occurs after bone marrow transplantation but the relative importance of graft versus host disease and other factors, such as infection, radiation, and drugs, has not been clearly established. We have studied liver status before and after bone marrow transplantation in 43 consecutive patients and have related this to survival and factors that are recognised to cause liver injury. Minor abnormalities of liver tests occurred in 21% of patients before grafting but this did not influence survival or the development of liver disease after transplantation. During the first 50 days after grafting, 83% of patients had abnormal liver tests which were more severe in patients who subsequently died. Alanine transaminase was significantly higher in non-survivors and appeared to predict survival early after transplantation. Only non-survivors developed clinical signs of liver disease. Severe liver disease was always associated with graft versus host disease and atypia of the small bile ducts was the most useful histological marker of hepatic involvement with this disease. Two of the patients with hepatic graft versus host disease also has hepatic veno-occlusive disease and three fatalities had opportunistic infection of the liver, although, in the latter, death was not due primarily to liver dysfunction. Previous hepatitis and androgen therapy could not be implicated as important causes of hepatic damage but chemotherapy for acute leukaemia and conditioning regimens for bone marrow transplantation appear to be the most important factors in the development of hepatic veno-occlusive disease.

Adolescent↗
PubMed1982

Comparison of plasma and intraluminal amino acid profiles in man after meals containing a protein hydrolysate and equivalent amino acid mixture.

Plasma and intraluminal amino acid profiles were compared in normal subjects 30, 60, 120, 180 minutes after meals containing either a peptide-rich protein hydrolysate (H) or an equivalent free amino acid mixture (AA) as the nitrogen source. Except for asparagine (30 minutes) and glutamine (30 and 60 minutes), which were absorbed to a significantly (p less than 0.05) greater extent from the peptide mixture, there were no significant differences in the plasma increments of the remaining 13 amino acids at any time interval after the meals. Positive correlations (p less than 0.01 or less) between the amino acid composition of the hydrolysate and amino acid meals and both (1) the post-prandial increments in the individual plasma amino acids and (2) the residual intraluminal amino acid content suggested that the amino acid composition of ingested protein, rather than specialised free amino acid and peptide transport systems, dictated the pattern of amino acid absorption. The studies provide no evidence that peptides rather than free amino acids are the ideal nitrogen source in elemental diets.

Adult↗
PubMed1982

Characterization and nutritional significance of peptide transport in man.

An in vivo intestinal perfusion technique has been used to investigate the characteristics of di- and tripeptides absorption in man. The results suggest that the model peptides studied were absorbed by a transport system separate to those responsible for mediating absorption of free amino acids. Two modes of intestinal uptake have been identified, namely transport of unhydrolysed peptides and transport of free amino acid residues liberated from the peptides by the action of brush border peptidases. A consistent finding was that amino acid residues were absorbed more rapidly from di- and tripeptides than from free amino acids. When amino acid uptake from four partial enzymic hydrolysates of protein was investigated, the 'kinetic advantage' conferred by peptides on amino acid uptake was found to be a generalized and concentration-dependent phenomenon. As later test meal studies showed that orally administered peptide mixtures were assimilated at least as rapidly as free amino acid mixtures, serious consideration could be given to using the less hypertonic and more palatable oligopeptide-based nitrogen sources in chemically defined elemental diets.

Amino Acids↗
PubMed1982

Portal hypertension.

Explore the source record for details and available documents.

Esophageal and Gastric Varices↗
PubMed1981

Trypsin enhancement of rotavirus infectivity: mechanism of enhancement.

The infectivity of most rotaviruses is enhanced by treatment with trypsin. We studied the mechanism of enhancement of examining the effect of trypsin on rotavirus infectivity, aggregation, early interactions with host cells, and structure. The results indicated that trypsin does not increase levels of infectious virus by dispersion of aggregates or affect the efficiency or rate of attachment of virus to cells. A fraction of virus that was not infections without trypsin treatment was found to attach to cells, but did not initiate antigen synthesis. When cells were infected with labeled, purified virus, increased levels of uncoated particles were found in cells infected with trypsin-treated virus. Infection of cells with trypsin-treated virus also led to greater levels of RNA synthesis early in the infection. The results suggest that trypsin converts a noninfectious fraction of virus into infectious virus by allowing this fraction to uncoat in the infected cell. Trypsin was found to cleave an 88,000-dalton structural polypeptide of bovine rotavirus generating 67,000- and 20,000-dalton cleavage products.

Animals↗
PubMed1981

Jejunal water and electrolyte secretion induced by L-arginine in man.

In this study a perfusion technique has been used to investigate jejunal secretion in response to the dibasic amino acid L-arginine. L-arginine at 5, 15, and 40 mmol/l in isotonic saline solutions induced net intestinal secretion of water and Na+. The structurally similar dibasic amino acid L-lysine caused net absorption at 5 and 15 mmol/l, and only modest net secretion of water and Na+ at 40 mmol/l, although absorption rates of the two amino acids were similar. D-arginine (15 mmol/l) was without effect on net water and Na+ absorption. L-arginine 15 mmol/l inhibited glucose-stimulated water and Na+ absorption when perfused in the same intestinal segment, but was without effect when perfused in separate jejunal or ileal segments. Parenteral chlorpromazine inhibited L-arginine induced jejunal water and Na+ secretion. Jejunal secretion induced by L-arginine thus appears not to be due to passive osmotic water flow, nor to release of circulating secretagogues. Stimulation of a mucosal secretory process is most likely to be the mechanism.

Adult↗