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Biomedical subjects

J Rogers

Publications and source records attributed to J Rogers.

At least 505 records · Page 28Linked to original sources
PubMed1980

Two mRNAs with different 3' ends encode membrane-bound and secreted forms of immunoglobulin mu chain.

During differentiation, B lymphocytes undergo a shift from expression of membrane-bound IgM to IgM secretion. The mu chains of membrane and secreted IgM, mum and mus, respectively, differ in the amino acid sequence of their carboxy terminal regions. In this paper, we demonstrate that mum and mus heavy chains are encoded by separate mRNAs of 2.7 and 2.4 kb, respectively. Restriction mapping and sequence analysis of mu cDNA clones from a myeloma tumor that produces both types of mu chain indicate that the mum and mus mRNAs are identical throughout the coding region up to the 3' end of the fourth constant region (Cmu 4) domain, but differ in their C terminal coding and 3' untranslated segments. From the nucleotide sequence of the mum cDNA clone, we predict the amino acid sequence of the 41-residue mum C terminal segment or "M" (membrane) segment. This sequence has characteristics consistent with its being a transmembrane peptide. Thus the mus chain has a 20-residue hydrophilic C terminal segment after the Cmu 4 domain, and the mum chain has a 41-residue C terminal segment containing a hydrophobic sequence. We propose that comparable C terminal segments also will be found in other membrane-bound immunoglobulin heavy chains.

Animals↗
PubMed1980

Senescent changes in a neurobiological model system: cerebellar Purkinje cell electrophysiology and correlative anatomy.

A within-subjects design was used to assess age changes in cerebellar Purkinje neurons. Four groups of naive male Sprague-Dawley rats, aged 3, 10, 20, and 28 months. underwent single cell recording for electrophysiological assessment of Purkinje cell firing patterns, followed by perfusion for glyoxylic acid induced catecholamine fluorescence. Cerebellar sections were photographed first by fluorescence microscope for catecholamines, and 2-3 weeks later for quantification of lipofuscin autofluorescence. Finally, these same tissues were treated with cresyl violet and photographed a third time to permit quantitative estimates of age changes in the number of Nissl staining Purkinje neurons. Electrophysiological studies revealed significant effect of age on a number of Purkinje cell firing parameters: in particular, increasing numbers of aberrant, very slow-firing cells were encountered in older animals. These cells showed normal climbing fiber mediated burst activity, but spontaneous simple spike firing rates 3-5 times less than normal. Rats exhibiting the highest numbers of such abnormal cells also exhibited the poorest Nissl staining. Conversely, good Nissl staining of Purkinje neurons in an old rat was a reliable predictor of relatively normal Purkinje cell firing. Lipofuscin was found to accumulate measurably in Purkinje neurons by 20 months of age, and to increase significantly thereafter. Deposition of the substance occurred almost exclusively at the apical pole of the soma. Our data suggest, however, that accumulation of lipofuscin in Purkinje neurons, as well as its reported accumulation in the inferior olive, is not a primary cause of electrophysiological dysfunction. There was no apparent age change in glyoxylic acid induced catecholamine fluorescence nor, in separate pharmacological studies, could any senescent alteration in cerebellar catecholamine levels be found.

Aging↗
PubMed1980

Forearm glucose uptake in cirrhosis and its relationship to glucose tolerance.

1. Oral glucose-tolerance tests (100 g) were carried out in six patients with stable well-compensated cryptogenic cirrhosis and in 12 control subjects. 2. In confirmation of previous studies, patients with cirrhosis had high post-glucose serum insulin levels and were glucose intolerant (mean incremental glucose area 954 +/- 186 compared with 482 +/- 35 mmol 3 h-1 l-1 in controls; P < 0.05). 3. Forearm arteriovenous differences of glucose and forearm blood flow were measured to estimate the proportion of the glucose load metabolized in peripheral tissues. Values in cirrhotic patients and control subjects (5614 +/- 1630 compared with 5344 +/- 672 mumol of glucose min-1 l-1 of forearm in 3 h) were similar despite higher glucose levels and sustained high insulin levels in the cirrhotic patients. 4. Peak lactate concentrations after glucose were of similar magnitude in the two groups (0.66 +/- 0.12 compared with 0.62 +/- 0.75 mmol/l) but in the patients with cirrhosis the peak occurred later and was more sustained. 5. The glucose intolerance of cirrhosis is primarily due to impaired hepatic retention of the glucose load. Insulin resistance in peripheral tissues may also be important since the higher insulin concentrations found in cirrhotic patients failed to enhance peripheral glucose uptake.

Adult↗
PubMed1980

A mechanism for RNA splicing.

The most abundant of the stable small nuclear RNAs of eukaryotic cells, U-1 small nuclear RNA, is exactly complementary to the consensus sequences at RNA splice sites. We propose that this RNA is the recognition component of the nuclear RNA splicing enzyme and forms base pairs with both ends of an intron so as to align them for cutting and splicing.

Animals↗
PubMed1980

The distribution and fate of 131I-labelled liposomes.

The distribution of 131I-labelled liposomes with sodium iodide entrapped in the aqueous core has been compared with that of a preparation containing iodinated phospholipid, following i.v. administration to rabbits. Liver uptake was observed initially with both liposomes, but the distribution of the former preparation soon became indistinguishable from that of [131I] sodium iodide. Iodine-131 was still detectable in the liver 150 h after administration of the phospholipid labelled material. Scintigrams showing the distributions of the radionuclides following administration of 131I-labelled liposomes and 99mTc-DTPA liposomes indicate that there may be some biliary clearance.

Animals↗
PubMed1980

A controlled study of self-help intervention for widows.

The authors conducted a 2-year study of postbereavement adaptation in 162 widows. Sixty-eight were paired with a widow contact who provided emotional support and practical assistance. The differences between the women receiving intervention and the controls at 6, 12, and 24 months after bereavement suggested that those receiving intervention followed the same general course of adaptation as control subjects but that the rate of achieving landmark stages was accelerated for the intervention group. The Goldberg General Health Questionnaire and two indices derived from the study questionnaire confirmed the hypothesized "pathway" of adaptation" through intra- and interpersonal adaptation to resolution of overall distress and the effectiveness of the intervention.

Adaptation, Psychological↗
PubMed1980

A self-help program for widows as an independent community service.

Community Contacts for the Widowed, a self-help group in Toronto, offers individual and group counseling and volunteer work to widows. Beginning as a demonstration project funded by the provincial health ministry, the program became an independent charitable organization in 1976. Like many new self-help groups, the program employs peers who receive training in helping their clients by establishing a one-to-one supportive relationship. These peers, called widow contacts, also arrange group sessions and conduct community education on behalf of the program. Although reliance on a self-referral process limits the number of lower-class, immigrant, and other widows unwilling to reach out for help, since 1976 the program has helped more than 1500 women through their bereavement.

Adaptation, Psychological↗
PubMed1980

The concept and measurement of continuity in primary care.

Continuity of care, a stated fundamental principle of family medicine, is reviewed in terms of its philosophy and definitions. A model of continuity in primary medical practice is proposed, consisting of five elements: the provider, consumer, encounter type, knowledge base, and environment of continuity. The elements are measurable, some more easily than others. There is need to define and operationalize the model more accurately in order to evaluate continuity in primary care medicine.

Attitude of Health Personnel↗
PubMed1979

Doctors accept a challenge: self-assessment exercises in continuing medical education.

A new approach to continuing medical education by distance learning has been implemented. A series of six patient-management problems or challenges were posted to 20 000 doctors throughout Britain. Each doctor had to decide on the diagnosis, investigations, and treatment of the patients described. The challenges covered problems that were important in the doctor's day-to-day work and were designed so that he could obtain immediate feedback about his decisions and compare his own responses with those of a specialist and those of his colleagues. Additional information was available by telephone and by post on request. The series has been well received and is being widely used.

Attitude of Health Personnel↗
PubMed1979

Sequence analysis of cloned cDNA encoding part of an immunoglobulin heavy chain.

The recombinant plasmid pH21-1 consists of mouse-derived complementary DNA (cDNA) in the E. coli plasmid pMB9. The mouse insertion has been completely sequenced, and encodes the CH3 domain and half the CH2 domain of the immunoglobulin gamma1 heavy chain. The predicted amino acid sequence differs at several positions from that previously published for this protein. The pattern of codon usage resembles that in some other eukaryotic messenger RNAs. A computer program has been used to predict the optimum secondary structure for the mRNA encoding the CH3 domain and the inter-domain junction.

Animals↗
PubMed1979

The organisation of cholesterol and ergosterol in lipid bilayers based on studies using non-perturbing fluorescent sterol probes.

The fluorescence properties of dehydroergosterol and cholesta-5,7,9-trien-3 beta-ol have been studied in organic solution, in aqueous dispersions and incorporated into aqueous lipid dispersions. The absorption spectra of aqueous dispersions of the probes are very different to those in organic solution, and aqueous dispersions are non-fluorescent. This can be attributed to micelle formation with dimerisation and/or aggregation in the micelles. Concentration quenching also occurs when sterols are incorporated into lipid bilayers, but relatively high fluorescence is observed even at a 1 : 1 steroid:lipid molar ratio. Further, the fluorescence is still polarized at these high molar ratios. We attribute this to the formation of ordered arrays of sterol molecules in the lipid bilayers. In these arrays the sterol molecules are organised in an end-to-end fashion, and face-to-face overlap of the sterols is prevented by the lipid molecules. Possible structures for 1 : 1 mixtures are presented.

Cholesterol↗