Search PubMed⌕ Search

Biomedical subjects

M C Brown

Publications and source records attributed to M C Brown.

At least 217 records · Page 12Linked to original sources
PubMed1977

Ultrasonic scanning of the thyroid gland as a guide to the treatment of the clinically solitary nodule.

This study examines the diagnostic accuracy of ultrasonic scanning in the recognition of multinodular goitre in 87 patients referred for examination who were thought by the referring clinician to have a single nodule in the thyroid gland. Twenty-five were found to have multinodular glands, 23 of which were correctly identified by ultrasound. Of those who had truly solitary nodules, ultrasonic scanning enabled us to identify all 23 who had cystic lesions and 35 out of the 39 who had predominantly solid lesions. The clinical significance of these observations in the management of patients with so-called 'single nodules' is discussed.

Adolescent↗
PubMed1976

Experience in mass Papanicolaou screening and cytologic observations of teen-age girls.

This report is based on a seven-year retrospective analysis of computerized data available from the Chicago Board of Health's Cancer Control Section and its Cytology Laboratory. All patients included were medically indigent. The cytologic specimens were obtained by the VCE technique; all Papanicolaou smears were classified with both the numerical and descriptive systems for abnormal cytology. The study cohort was composed of 33,641 teen-age patients through age 19; 58 (1.7/1,000) had abnormal cytology (Class III, IV, or V). In Chicago, from 1962 through 1969, approximately 25 per cent of the total patient load were teen-agers under the age of 19 with an extremely low yield of suspect cytology: Class III = 1.6 per month; Class IV = 0.1 per month; Class V = 0.0 per month. The Chicago Board of Health has reduced the number of Papanicolaou smears taken on young women under the age of 19; however, this conceptual approach does not exclude women under age 19 who epidemiologically and/or clinically warrant the implementation of a Papanicolaou smear with the use of Friedell's "biologic age of the cervix" formula.

Adolescent↗
PubMed1976

Demonstration of an idiotypic antigen on a monoclonal cold agglutinin and on its isolated heavy and light chains.

A potent anti-idiotype serum produced in a rabbit immunized with the isolated heavy chains of an IgM cold agglutinin "Col" was rendered specific by solid-state adsorptions. The anit-Col idiotype was shown to bind specifically to both isolated Col heavy (mu) and light (kappa) chains as well as to intact Col IgM by three methods: (i) reversal of anti-idiotype inhibition of Col cold agglutinin in an automated hemagglutination-inhibition assay system; (ii) adsorption of the anti-idiotype by affinity gels consisting of Col IgM, mu, or kappa chains covalently coupled to Sepharose 2B; (iii) binding of Col IgM and its isolated chains by an anti-idiotype affinity gel. Fragments of Col light chain lacking constant region determinants but still capable of inhibiting anti-idiotype were produced by limited pepsin digestion of the light chains. The finding of shared idiotypic determinants on isolated heavy and light chains of a monoclonal antibody suggests that these chains share a common sequence in a hypervariable region. As an extension of the gene insertion theory of Wu and Kabat, we postulate that genes coding for hypervariable regions may be available for insertion into the DNA for both heavy and light chains.

Agglutinins↗
PubMed1976

Regeneration of afferent and efferent fibres to muscle spindles after nerve injury in adults cats.

1. The nerves to cat peroneus longus and tenuissimus muscles were either cut or crushed close to the muscle and the afferent and efferent nerve supply to the muscle spindles was studied electrophysiologically between 2 and 32 weeks later. 2. Recovery was more rapid and complete after crush than section for both afferent and efferent fibres. After recovery from either procedure normal primary and secondary afferents and static and dynamic gamma efferent fibres were found. 3. Some abnormally occurring neurones were found. One group consisted of beta fibres which had a static action on muscle spindles. Static beta fibres are very rarely found in normal muscles. 4. The results indicate that some guidance mechanism exists which after crush injuries of nerves may restore muscle receptor function almost to normal. Even after nerve section some muscle spindles may become correctly reinnervated.

Action Potentials↗
PubMed1976

Polyneuronal innervation of skeletal muscle in new-born rats and its elimination during maturation.

1. The events taking place during the elimination of polyneuronal innervation in the soleus muscle of new-born rats have been studied using a combination of electrophysiological and anatomical techniques. 2. Each immature muscle fibre is supplied by two or more motor axons which converge on to a single end-plate. There was no sign of electrical coupling between muscle fibres receiving multiple synaptic inputs. By the end of the second week after birth virtually all muscle fibres are innervated by only a single motor axon. 3. The average tension produced by individual motor units, measured in terms of the percentage of the total muscle twitch tension, declined dramatically during the first 2 weeks after birth. During this period there was no significant change in the number of motor neurones innervating the soleus muscle. Thus, the disappearance of polyneuronal innervation reflects a decrease in the number of peripheral synapses made by each motor neurone. 4. The decline in motor unit size was delayed, but not ultimately prevented, by the early surgical removal of all but a few motor axons to the soleus muscle. This procedure also caused a delay in the removal of polyneuronal innervation involving the remaining motor units. 5. Following a crush of the soleus nerve in neonatal animals, regenerating axons usually returned to the original end-plates. Polyneuronal innervation was extensive at early stages of re-innervation and it disappeared during the second week after birth just as in normal muscles. 6. Cross-innervation of neonatal muscles by an implanted foreign nerve caused a rapid disappearance of cholinesterase at denervated original end-plates and in most fibres prevented re-innervation by the original nerve. In the small proportion of fibres that did become innervated through both the foreign and original nerves the end-plates were more than 1 mm apart, and both foreign and original nerve end-plates could persist indefinitely. 7. Many cross-innervated fibres received multiple inputs through the foreign nerve. Some foreign end-plates were separated by distances ranging up to 1 mm. Polyneuronal innervation through the foreign nerve was completely eliminated during maturation but over a slightly longer period than in normal muscles. Apparently the elimination process can act over a distance up to but not much more than 1 mm. 8. These observations suggest that there are several factors influencing the elimination of redundant inputs in immature muscles. Individual motor neurones appear to have an inherent tendency to withdraw the majority of their original complement of peripheral terminals. The determination of which particular synapses are to survive, however, seems to be made in the periphery by a selection among all the synapses that innervate a limited region of each muscle fibre. There may be a competitive interaction among synapses in which those belonging to smaller motor units are less likely to be eliminated, thereby leading to a relatively uniform size of the motor units in the soleus.

Animals↗
PubMed1975

Evidence that the major cell suface glycoprotein of the TA3-Ha carcinoma contains the Vicia graminea receptor sites.

The Vicia graminea lectin receptor of the nonstrain-specific TA3-Ha mammary carcinoma ascites cell of the strain A mouse was shown to be predominantly or exclusively on a large mucin-type surface glycoprotein. TA3-Ha cells adsorbed the lectin in amounts equivalent to 5-9 mg of this glycoprotein/10-9 cells, which was 100-400 times greater than by the strain-specific TA3-St cell, employed as a control. Release of sialic acid by incubation with neuraminidase increased the adsorptivity of the TA3-Ha cell three to fourfold and of the TA3-St cell six- to ten fold. Proteolysis of TA3-Ha cells released into the supernatant solutions approximately the same amount of inhibitory activity, equivalent to approximately 5 mg of the glycoprotein and only 10 per cent of the original adsorptivity remained on the cells. By contrast, TA3-St cells released no detectable inhibitory activity into the medium when subjected to similar proteolysis, even after neuraminidase treatment. Upon fractionation of released material on gel columns, high-molecular weight material and activity were found in the same fractions, but purified samples differed significantly in specific activity and carbohydrate composition. Heterogeneity in the carbohydrate moieties of the macromolecules was further demonstrated by incubation of these samples with neuraminidase, which enhanced their inhibitory activities from two- to tenfold.

Animals↗
PubMed1975

Reversible loss in suspension culture of a major cell-surface glycoprotein of the TA3-Ha mouse tumor.

A major cell-surface glycoprotein of the TA3-Ha ascites mammary adenocarcinoma diminished during transfer from ascites growth to cell growth in suspension culture. A sensitive, hemagglutination-inhibition assay that used a lectin from Vicia graminea seeds indicated approximately a 50% loss after 7-10 days of culture and a 90% loss after 2 months. These findings were corroborated by carbohydrate and amino acid analysis with gas-liquid chromatography of trypsin glycopeptides released from the cell surface. Repassage of the cultured cells in vivo caused the reappearance of the surface glycoprotein.

Adenocarcinoma↗
PubMed1975

An investigation into the site of termination of static gamma fibres within muscle spindles of the cat peroneus longus muscle.

1. The distribution of static fusimotor fibres to intrafusal muscle fibres of cat peroneus longus muscle spindles was investigated using the glycogen-depletion technique of Edström & Kugelberg (1968). Single static gamma fibres were stimulation intermittently at high rates for 3 hr with the blood supply occluded for some of this time. Subsequently the portion of muscle containing the activated spindles was fixed, sectioned and stained for glycogen with the periodic acid-Schiff (PAS) method. 2. Ten static axons caused depletion in eleven spindles. In five of these the only glycogen-depleted fibres were nuclear chain fibres. In the other six spindles one nuclear bag fibre was depleted in addition to chain fibres and this was always the larger of the two within the spindle. 3. These results on a medium-sized hind limb muscle are compared with findings concerning the distribution of static gamma fibre axons previously investigated only in very small muscles. The results agree in showing that nearly all static gamma fibres innervate nuclear chain fibres but that in 50-75% of the times in which static gamma fibres innervate spindles the distribution is to bag fibres as well as to chain fibres. The interpretation to be put upon this is uncertain. One possibility with which the results from peroneus longus are consistent is that the bag fibres which are usually innervated by static axons are the 'intermediate' bag fibres whose ultrastructure has recently been shown to resemble that of chain fibres.

Animals↗
PubMed1974

In vivo release of glycoprotein I from the Ha subline of TA3 murine tumor into ascites fluid and serum.

Previous studies have demonstrated that a unique glycoprotein can be cleaved by trypsin from the plasma membrane of the Ha, but not the St, subline of the TA(3) murine mammary adenocarcinoma. Using an automated quantitative method for measurement of trypsincleaved fragments (glycoprotein fraction I) by inhibition of Vicia graminea lectin hemagglutination, we find evidence that glycoprotein fraction I-like molecules appear in the ascites fluid and serum of the Ha-bearing, but not the St-bearing, syngeneic mice. These molecules were shown by gel filtration to be larger than the trypsincleaved glycoprotein fraction I but have a carbohydrate composition very similar to glycoprotein fraction I. It is likely that these ascites and serum glycoproteins have been released in vivo from the membranes of the viable Ha tumor cells. In view of the ability of the Ha, but not the St, cells to grow in allogeneic recipients, it is possible that these circulating membrane-derived molecules may be playing a blocking role in the immune response to the tumor.

Animals↗