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Biomedical subjects

J Perry

Publications and source records attributed to J Perry.

At least 145 records · Page 8Linked to original sources
PubMed1990

Methylthioadenosine serves as a single carbon source to the folate co-enzyme pool in rat bone marrow cells.

[ribose-U-14C]Methylthioadenosine (MTA) was prepared by incubating methionine with [14C-U]ATP in the presence of methionine adenosyltransferase and the resulting S-adenosylmethionine was heated to release MTA. Labelled [14C]MTA, when incubated with rat bone marrow cells, yielded [14C]formate which was used in the synthesis of adenine and guanine. Unlike 14C from sodium, formate, serine and glycine, there was no decline in 14C utilization from MTA with bone marrow cells from rats in which cobalamin had been inactivated by exposure to nitrous oxide. It was concluded that methionine via MTA is a significant contributor of single-carbon units at the formate level of oxidation and that this pathway is maintained in cobalamin 'deficiency'.

Adenine↗
PubMed1990

Cobalamin inactivation induces formyltetrahydrofolate synthetase.

Loss of cobalamin function produces profound changes in the metabolism of formate. There is impaired synthesis of formyltetrahydropteroylglutamate synthetase (CHO-H4PteGlu), accumulation of endogenous formate and impaired utilization of [14C]formate. There are contradictory reports on the effect of cobalamin inactivation on CHO-H4PteGlu synthetase. This study confirms a significant increase in synthetase activity following cobalamin inactivation.

Analysis of Variance↗
PubMed1990

Monoclonal antibodies to ROS 17/2.8 cells recognize antigens, some of which are restricted to osteoblasts and chondrocytes.

We have raised a panel of 15 monoclonal antibodies (MAbs) recognizing cell surface antigens of the rat osteoblast-like cell line ROS 17/2.8. The MAbs were selected on the basis of preferential binding to ROS 17/2.8 cells compared to ROS 25/1 cells. Immunohistochemical studies of antigen localization on cryostat sections of rat calvaria, long bone, and soft tissues demonstrated that five of these MAbs, UBIM 1, 2, 3, 12, and 17, recognize antigens that are restricted to normal rat osteoblasts and chondrocytes. The antigens appear to be localized to the cell surface of the osteoblast, with no apparent staining of bone matrix in either undecalcified or decalcified sections. In vitro, these MAbs recognize cell surface antigens present on two additional cell lines, ROS 24/1 and Rat 2 cells, and on the adherent cell population cultured from rat long bone marrow. Of these MAbs, three (UBIM 1, 2, and 3) recognize high-molecular-weight antigens of Mr 200,000-225,000. This study has also identified cell surface antigens of ROS 17/2.8 cells that are not expressed by osteoblasts in vivo. MAbs UBIM 9 and 21 bind to marrow cells in long bone sections, to the 7-day-old nonadherent cell population from cultured marrow, and to lymphoid tissue in sections of spleen. Another four MAbs (UBIM 10, 11, 14, and 22) bind to a variety of cells and tissues both in vitro and in vivo. Studies of the interactions of this panel of MAbs with osteogenic tissues and cell lines may have an important impact on the understanding of osteoblast physiology.

Animals↗
PubMed1990

Glucose tolerance in pregnancy: ethnic variation and influence of body habitus.

Little is known about ethnic differences in glucose tolerance during pregnancy. In this study we examined 3366 Hispanic, Chinese, black, and non-Hispanic white women in a universal screening program for gestational diabetes mellitus. After maternal age and body mass index were controlled, Chinese women had a significantly higher serum glucose level 1 hour after 50 gm of oral glucose (134.8 +/- 1.2, mean +/- SE) than any of the remaining three groups. Black women had a significantly lower value (113.3 +/- 1.3, mean +/- SE) than either Chinese or Hispanic women (124.4 +/- 0.9, mean +/- SE). Results for Hispanic women and non-Hispanic white women (121.4 +/- 1.6, mean +/- SE) were not different. The screening glucose levels of Chinese women were substantially higher than other ethnic groups even when women with gestational diabetes were removed from the analysis, indicating that the observed differences were not solely due to a higher frequency of gestational diabetes among the Chinese. The incidence of gestational diabetes was significantly greater for Chinese (7.3%) and Hispanic (4.2%) women than for black (1.7%) and non-Hispanic white (1.6%) women. Among women who had a 3-hour glucose tolerance test, the area under the glucose curve was significantly associated with maternal age and body mass index. The demonstrated heterogeneity of glucose tolerance between ethnic groups may be of importance in determining the threshold for diabetic fetopathy, and it is possible that ethnicity-specific standards will need to be developed.

Asian People↗
PubMed1990

5S rRNA sequences of representatives of the genera Chlorobium, Prosthecochloris, Thermomicrobium, Cytophaga, Flavobacterium, Flexibacter and Saprospira and a discussion of the evolution of eubacteria in general.

5S rRNA sequences were determined for the green sulphur bacteria Chlorobium limicola, Chlorobium phaeobacteroides and Prosthecochloris aestuarii, for Thermomicrobium roseum, which is a relative of the green non-sulphur bacteria, and for Cytophaga aquatilis, Cytophaga heparina, Cytophaga johnsonae, Flavobacterium breve, Flexibacter sp. and Saprospira grandis, organisms allotted to the phylum 'Bacteroides-Cytophaga-Flavobacterium' and relatives as determined by 16S rRNA analyses. By using a clustering algorithm a dendrogram was constructed from these sequences and from all other known eubacterial 5S RNA sequences. The dendrogram showed differences, as well as similarities, with respect to results obtained by 16S RNA analyses. The 5S RNA sequences of green sulphur bacteria were closely related to one another, and to a cluster containing 5S RNA sequences from Bacteroides and its relatives, including Cytophaga aquatilis. 5S RNA sequences of all other representatives of the 'Bacteroides-Cytophaga-Flavobacterium' phylum as distinguished by 16S RNA analysis failed to group with Bacteroides and related clusters. On the basis of 5S RNA sequences, Thermomicrobium roseum clustered with Chloroflexus aurantiacus, as was expected from 16S RNA analysis.

Base Sequence↗
PubMed1990

Formate metabolism in the cobalamin-inactivated rat.

Endogenous formate levels in blood and liver were assayed in rats both after inactivation of cobalamin (Cbl) by exposure to N2O as well as in air-breathing controls. The uptake of [14C]formate by tetrahydrofolate (H4folate) in bone marrow cells and liver homogenate and the incorporation of [14C]formate into purine, pyrimidine, methionine, serine and choline, was measured. There was a significant accumulation of endogenous formate following Cbl inactivation. There was impaired utilization of [14C]formate for single unit carbon (C1 unit) transfers mediated by folate in Cbl-inactivated tissues, other than for synthesis of adenine. The impairment was not accompanied by any accumulation of labelled methylH4folate indicating that methylfolate trapping played no part in impaired single carbon unit transfer. The effect of Cbl lack was a failure to form formylH4folate so that formate accumulated. The reason for this is not known.

Animals↗
PubMed1990

Instrumented gait analysis after selective dorsal rhizotomy.

In an attempt to assess quantitatively the effects of selective dorsal rhizotomy on ambulatory patients with cerebral palsy, instrumental gait analysis was used to document and compare changes following surgery. Stride characteristics, dynamic surface electromyography, foot-floor contact patterns and motion of the thigh, knee and ankle were analysed. 14 patients (seven independent ambulators, seven using assistive devices) aged between 4.6 and 23.5 years were tested before surgery and again six to 14 months later. After surgery, the seven independent walkers retained the same level of function and one of the assisted walkers had progressed to independent walking, but the other six still used the same device as before surgery. Selective dorsal rhizotomy reduces spasticity and improves gait dynamics, but does not change patterns of muscle activation during walking.

Adolescent↗
PubMed1990

Variations in the carbohydrate regions of Bordetella pertussis lipopolysaccharides: electrophoretic, serological, and structural features.

Structural and immunological differences between the two components that are usually present in unequal quantities in Bordetella pertussis endotoxin preparations and are visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis have been studied by using strains 1414, A100, and 134, all in phase I. According to analyses by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis and thin-layer chromatography, the minor (8%) component of the endotoxin of strain 1414 (endotoxin 1414) appeared to be the predominating component of endotoxins A100 and 134. The masses of the carbohydrate chains isolated from endotoxin A100 and from the major component of endotoxin 1414 were 1,649 and 2,311 atomic mass units, respectively, as determined by 252Cf plasma desorption mass spectrometry. Comparison of the 1H nuclear magnetic resonance spectra of these chains established that four N-acetyl groups, an N-methyl group, and a 6-deoxy function, which characterize the nonreducing, distal trisaccharide of the glycose chain of strain 1414, were absent from that of strain A100. The antigenicity of endotoxin 1414, as measured by enzyme-linked immunosorbent assay, was higher than that of endotoxin A100, but fell below it when the glycose chain of endotoxin 1414 was deprived of seven sugars by treatment with nitrous acid. This observation suggests that at least three (distal, proximal, and intermediate) regions of the glycose chain of endotoxin 1414 carry antigenic determinants. One of these, located in the distal trisaccharide, is absent from both endotoxins A100 and 134.

Bordetella pertussis↗
PubMed1990

Methylation of DNA in megaloblastic anaemia.

Methylation of cytosine residues in DNA samples, collected before and serially after cobalamin treatment from patients with cobalamin deficiency, was studied using restriction endonucleases Hpa II and Msp I and an epsilon globin gene probe. There was no evidence of hypomethylation in any of the samples. It was concluded that although hypomethylation of metabolites such as choline occurs, that of DNA is preserved in megaloblastic anaemia.

Anemia, Macrocytic↗
PubMed1990

Below-knee amputee gait with dynamic elastic response prosthetic feet: a pilot study.

The purpose of this pilot study was to investigate some of the new dynamic elastic response (DER) prosthetic feet compared to the SACH foot and determine if any demonstrated trends of producing the most optimum gait. We investigated the gait of five below-knee amputees while wearing four different DER feet (Flex-Foot, Carbon Copy II, SEATTLE, STEN) and a standard SACH foot. Each subject used each foot for 1 month prior to in-depth gait analysis and energy expenditure testing at the Pathokinesiology Laboratory. Minimal differences in either free or fast walking were noted between the five feet. The Flex-Foot resulted in significantly different gait kinematics at the "ankle" compared to the other four feet, however, this foot did not produce an increased velocity nor an improved energy cost. The results of this pilot study indicated that during free or fast-paced walking on level ground there were no clinically significant advantages of any one of the feet tested. Based on this pilot data, recommendations are made for future studies including appropriate sample size.

Adult↗
PubMed1990

Effect of an unrestricted knee-ankle-foot orthosis on the stance phase of gait in healthy persons.

Twenty healthy women (mean age: 25 +/- 3.6 years) were studied for postural adaptations produced when walking with unrestricted knee-ankle-foot orthoses. Stride characteristics, motion, floor reaction forces and their torques, and indwelling electromyographic activity of the lower gluteus maximus, as well as the long head of the biceps femoris, vastus lateralis, and soleus muscles were all measured during barefoot and orthosis walking. Wearing a knee-ankle-foot orthosis increased stride length and decreased cadence and stance duration. The subjects walked in slightly more plantar flexion, knee flexion, and hip flexion, while increasing the duration of the corresponding floor reaction torques, resulting in an activity increase of the vastus lateralis, soleus, and biceps femoris muscles. These results, obtained in healthy subjects, show a definite effect of an unrestricted knee-ankle-foot orthosis on gait.

Adult↗
PubMed1990

Continuous warm blood cardioplegia: a new technique for myocardial protection.

Hypothermia is used to prolong the safe period of ischemic arrest by reducing the heart's oxygen demands. Due to this effect, hypothermia has been the fundamental component of most methods of myocardial protection during cardiac surgery. However, hypothermia has a number of unwanted side effects, such as detrimental effects on enzyme function, energy generation, and cell membranes. Since electromechanical arrest accounts for 90% of myocardial oxygen consumption, arresting the heart with chemical cardioplegia will reduce O2 consumption dramatically. Therefore, if the resting (arrested) heart is continuously perfused with oxygenated blood cardioplegia, one can easily provide the remaining 10% of O2 that it requires. Under these conditions, the need for hypothermia becomes questionable. In this paper, we describe the perfusionist's experience using the antegrade and retrograde technique of continuous warm blood cardioplegia.

Blood↗
PubMed1990

Pathologic gait.

The diagnosis of gait deviations and their causes requires three levels of knowledge. First is an awareness of the functional limitations caused by each type of abnormality (contracture, muscle weakness, pain, and spasticity). Second is familiarity with normal function. Third is having a trained eye or gait analysis system that is capable of identifying the gait deviations. Once diagnosis is complete, a fourth requirement is the ability to use the findings to set up an appropriate treatment regimen.

Ankle Joint↗
PubMed1990

Validity of self-report of adaptive behavior skills by adults with mental retardation.

The validity of self-reports of 48 adults with mental retardation of daily living competency using the recently revised Vineland Adaptive Behavior Scales (Sparrow, Balla, & Cicchetti, 1984) was investigated. Self-report was compared to standard Vineland interviews of subjects' program counselors and to demonstrated competency in a real-life setting. On domains measuring adaptive skills, the subject and counselor interviews yielded highly consistent results. On the optional Maladaptive Behavior domain, however, the subjects with mental retardation underreported problematic behavior. Response validity and implications for use of self-report for program planning and placement decisions were discussed.

Activities of Daily Living↗
PubMed1989

Oxidation of 5-methyltetrahydrofolate in cobalamin-inactivated rats.

Rats were exposed to nitrous oxide, which inactivates cob(I)alamin (Cbl). As in air-breathing rats methionine administration led to the conversion of hepatic 5-methyltetrahydrofolate (MeH4 folate) into formyltetrahydrofolate. The recovery of MeH4 folate levels in liver after its oxidation initiated by methionine was noted and the rate compared with that for air-breathing rats. Oxidation of MeH4 folate was less complete and occurred more slowly in Cbl-inactivated rats as compared with controls. However, recovery of MeH4 folate levels was more rapid in Cbl inactivation. S-Adenosylmethionine did not produce a significant change in MeH4 folate levels in Cbl-inactivated rats, whereas it did so in air-breathing animals.

Animals↗
PubMed1989

Regulation of 5-methyltetrahydrofolate synthesis.

After an intraperitoneal injection of 100 mumol of methionine to rats, there is rapid oxidation of the methyl group of hepatic 5-methyltetrahydrofolate to formate and CO2. Recovery of the methylfolate level starts 2.5 h after the methionine injection, when the hepatic methionine level and the S-adenosylmethionine/S-adenosylhomocysteine ratio have returned to baseline values. S-Adenosylmethionine concentration is still elevated at this time.

Animals↗