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Biomedical subjects

M Foster

Publications and source records attributed to M Foster.

At least 19 recordsLinked to original sources
PubMed1992

Developmental pathways through childhood for children treated in a neonatal intensive care unit.

We report the findings of a longitudinal study of children who were treated in the neonatal intensive care units in 1975-78. Relationships are described between measures of conditions and treatments of both mothers and newborns during the perinatal period and measures representing motor, neurological, developmental, and ability functions of the children at 15 months, 4 years and 7 years. The results of multivariate and path analyses are presented in which a latent variable approach is used to characterize the covariation between signs, symptoms, and treatment in the perinatal period and the major dimensions of functioning at the follow-up occasions. Included among several noteworthy pathways between the latents of the various periods were ones from fetal distress, asphyxia, early crisis, intraventricular hemorrhage, anemia of prematurity, and number of days in the unit.

Age Factors↗
PubMed1992

[Augmentin].

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Adult↗
PubMed1992

Combating MRSA.

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Drug Resistance, Microbial↗
PubMed1991

Evidence for essential histidine and cysteine residues in calcium/calmodulin-sensitive cyclic nucleotide phosphodiesterase.

Ca/calmodulin-sensitive cyclic nucleotide phosphodiesterase (CaM-PDE) is an important enzyme regulating cGMP levels and relaxation of vascular smooth muscle. This modification study was conducted mostly with bovine brain CaM-PDE to identify essential functional groups involved in catalysis. The effect of pH on Vmax/Km indicates two essential residues with pKa values of 6.4 and 8.2. Diethyl pyrocarbonate (DEP), a histidine-modifying agent, inhibits CaM-PDE with a second-order rate constant of 130 M-1 min-1 at pH 7.0 and 30 degrees C. Activity is restored by NH2OH. The pH dependence of inactivation reveals that the essential residue modified by DEP has an apparent pKa of 6.5. The difference spectrum of the intact and DEP-treated enzyme shows a maximum between 230 and 240 nm, suggesting formation of carbethoxy derivatives of histidine. The enzyme is also inactivated by N-ethylmaleimide (NEM) and 5,5'-dithiobis-(2-nitrobenzoic acid), both sulfhydryl-modifying agents, with the latter effect reversed by dithiothreitol, which suggests inactivation resulting from modification of cysteine residue(s). Partial inactivation of the enzyme by DEP or NEM results in an apparent decrease in the Vmax without a change in the Km or the extent of CaM stimulation. The rate of inactivation by DEP is greater in the presence than in the absence of Ca/CaM. A substrate analogue, Br-cGMP, and the competitive inhibitor 3-isobutyl-1-methylxanthine partially protect the enzyme against inactivation by DEP or NEM, suggesting that the modification of histidine and cysteine residues occurs at or near the active site. DEP also inactivated porcine brain CaM-PDE.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

The relation between perinatal conditions and developmental outcome in low birthweight infants. Comparison of two cohorts.

We have compared the relations between perinatal conditions and developmental outcomes at age four years for two cohorts of children with birthweights 2,300 g or less, who did not develop cerebral palsy--one from Southeastern Wisconsin (children born 1975-76) and the other from Copenhagen (children born 1980-82). We examined the general effects of parental education and socioeconomic status, the use of Cesarean section, the degree of prematurity and neonatal complications on outcome. The methods of latent path structural analysis were used to form two models among 15 latent variables: one for children from Copenhagen and a similar model for children from Wisconsin. The impact of parental education and socioeconomic status was somewhat greater in Wisconsin. Several neonatal complications were related to outcome in Wisconsin: the early condition of the infant, use of a respirator, pneumothorax, and anemia/apnea. The only neonatal complication with a significant relation to outcome in Copenhagen was pneumothorax and to a much lesser degree major germinal layer haemorrhage. The degree of prematurity per se had a greater impact in Copenhagen. The use of Cesarean section and mechanical ventilation in the smallest infants was much more frequent in Denmark, but no association could be shown between this increased use and improved developmental outcome.

Child Development↗
PubMed1979

Imaging by nuclear magnetic resonance and its bio-medical implications.

The distribution of proton spin concentration (water concentration) and the proton spin-lattice relaxation time (T1) can be imaged in a sample by placing it in a magnetic field gradient, applying appropriate radio-frequency (rf) pulses, and measuring the rf radiated from the sample. The Aberdeen machine is designed to image the human body in vivo at 400 gauss and 1.7 MHz. The spatial resolution predicted is about 1 cm for a 20% difference of T1. Measurements of T1 for small samples of tissue in vitro show a five-fold range of values for some soft tissues. Breast tumours and liver metastases have shown T1 values very different from the surrounding tissue. The method has the potential of perhaps imaging any pathology which changes water concentration, forms fluid pools or affects the binding of water to macromolecules. The potential hazards, which need more investigation, seem slight.

Animals↗
PubMed1979

Decreased hybrid susceptibility to murine myeloma grafts.

The behavior of BALB/c myeloma transplants in (C57BL/10 X BALB/c)F1 hybrids was investigated. The F1 hybrids were less susceptible to the grafts than were the parental BALB/c hosts. Host susceptibility was X-ray and cyclophosphamide sensitive, but an immune hypothesis was not favored since no memory was demonstrable. Males were less susceptible than females, and rabbit antithymus serum had no effect on susceptibility.

Animals↗
PubMed1979

Genetics of F1 hybrid susceptibility to myeloma grafts.

The genetics of hybrid susceptibility of parental myeloma transplants in histocompatible F1 hybrids was investigated. Various inbred mouse strains and their descendant congenic lines were crossed with BALB/C mice to produce appropriate F1 hybrids. Genetic inferences were drawn from the comparison of the frequencies of tumor graft takes among congenic combinations. Hybrids containing the C57BL/10 genetic background were less susceptible to myeloma transplants than were hybrids of other genotypes. Both H-2-associated and non-H-2-associated genetic factors played significant roles in determining host susceptibility to the transplants. The D end of the major histocompatibility complex did not play a predominant role in determining hybrid susceptibility in C57BL-derived F1 hybrids.

Animals↗
PubMed1979

Macrophages in experimental and human brain tumors. Part 1: Studies of the macrophage content of experimental rat brain tumors of varying immunogenicity.

Although the presence of lymphoreticular cells within tumors has been recognized for over 100 years, it is only within the last decade that the concept has arisen that standard histological examination techniques may lead to an underestimation of the true extent of tumor infiltration by lymphoreticular cells, and particularly by macrophages. The macrophage content of certain systemic tumors has been correlated with their immunogenicity and growth characteristics. Since the central nervous system is to some extent an "immunologically privileged site" and contains within it specialized reticuloendothelial cells called microglia, the authors determined the macrophage content of three rodent brain-tumor cell lines, and attempted to correlate this macrophage content with their immunogenicity and growth characteristics. Their findings indicate a direct correlation between the immunogenicity and macrophage content of these three neural tumor cell lines.

Animals↗
PubMed1979

Macrophages in experimental and human brain tumors. Part 2: studies of the macrophage content of human brain tumors.

The authors have analyzed 47 tumors of the central nervous system (11 glioblastomas, nine meningiomas, three medulloblastomas, 12 assorted primary neural tumors, and 12 brain metastases) for their content of macrophages. Cell suspensions were prepared by enzymatic digestion and macrophages were quantitated by IgGEAC rosette formation. Adsorption of sensitized indicator cells (EA) to sections of tumor was used as a measure to determine the distribution of IgGFc receptor-positive cells within the tumors and to serve as a control for selective release of IgGFc receptor-positive cells by enzyme digestion. The 11 glioblastomas had a mean macrophage content of 45% (range: 8% to 78%), the nine meningiomas had a mean of 44% (range: 5% to 81%), the three medulloblastomas a mean of 6% (range 2% to 15%), and the metastatic tumors a mean of 24% (range: 4% to 70%). Adsorption of EA demonstrated that IgGFc receptor-positive cells were distributed throughout the tumor mass, although different types of patterns were observed. There was an excellent correlation between the percent of IgGEAC positive cells in suspensions and the extent of EA adsorption to the tumor sections. Compared to systemic neoplasms, most nervous system tumors have a high macrophage content. It is possible that the high macrophage content of brain tumors is related to their immunogenicity, and may be a partial explanation for tha rarity of brain-tumor metastases.

Brain Neoplasms↗
PubMed1978

Low-dose insulin infusions in diabetic patients with high insulin requirements.

Six patients with high insulin requirements (range 120-3000 units daily) have been infused with much smaller doses (range 50-63 units daily) of insulin intravenously. All six maintained adequate glucose homoestasis on this regimen. It is suggested that subcutaneous tissue at the site of injection may alter insulin or impair its absorption. Insulin resistance in some patients may be due to these mechanisms.

Adolescent↗
PubMed1977

Electron spin resonance as a useful technique in the management of Hodgkin's disease.

Electron spin resonance spectroscopy has proved a useful and simple technique for the measurement of levels of caeruloplasmin and iron transferrin in whole blood from 50 patients with Hodgkin's disease. Those patients with clinically active disease show higher caeruloplasmin levels and lower iron transferrin levels than those with inactive disease. The results indicate that these tests are good indicators of the state of the disease and that serial measurement of these parameters may help in early prediction of clinical reactivity and in monitoring response to treatment. The combined information from iron transferrin and caeruloplasmin levels appears to be more predictive than that from the erythrocyte sedimentation rate and neutrophil alkaline phosphatase score.

Adolescent↗
PubMed1977

Electron spin resonance measurements of blood caeruloplasmin and iron transferrin levels in patients with non-Hodgkin's lymphoma.

Caeruloplasmin and iron transferrin level were measured in blood of patients with non-Hodgkin's lymphoma in different stages of disease activity and compared with erythrocyte sedimentation rate and NAP level in the same samples. It was found that both caeruloplasmin level and sedimentation rate showed a slight increase in mean level in patients with active disease as compared with those in remission, particularly in the group of patients with poorly or undifferentiated diffuse disease. No difference was observed in levels of iron transferrin or NAP. Both caeruloplasmin and sedimentation rate showed occasional abnormal values in patients in remission but in most cases where both were elevated the patients subsequently entered a more active phase of the disease.

Adult↗
PubMed1975

Identification of essential arginyl residues in cytoplasmic malate dehydrogenase with butanedione.

The inactivation of cytoplasmic malate dehydrogenase (L-malate: NAD+ oxidoreductase, EC 1.1.1.37) from porcine heart and the specific modification of arginyl residues have been found to occur when the enzyme is inhibited with the reagent butanedione in sodium borate buffer. The inactivation of the enzyme was found to follow pseudo-first order kinetics. This loss of enzymatic activity was concomitant with the modification of 4 arginyl residues per molecule of enzyme. All 4 residues could be made inaccessible to modification when a malate dehydrogenase-NADH-hydroxymalonate ternary complex was formed. Only 2 of the residues were protected by NADH alone and appear to be essential. Studies of the butanedione inactivation in sodium phosphate buffer and of reactivation of enzymatic activity, upon the removal of excess butanedione and borate, support the role of borate ion stabilization in the inactivation mechanism previously reported by Riordan (Riordan, J.F. (1970) Fed. Proc. 29, Abstr. 462; Riordan, J.F. (1973) Biochemistry 12, 3915-3923). Protection from inactivation was also provided by the competitive inhibitor AMP, while nicotinamide exhibited no effect. Such results suggest that the AMP moiety of the NADH molecule is of major importance in the ability of NADH to protect the enzyme. When fluorescence titrations were used to monitor the ability of cytoplasmic malate dehydrogenase to form a binary complex with NADH and to form a ternary complex with NADH and hydroxymalonate, only the formation of ternary complex seemed to be effected by arginine modification.

Adenosine Monophosphate↗