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Biomedical subjects

J Mitchell

Publications and source records attributed to J Mitchell.

At least 379 records · Page 21Linked to original sources
PubMed1982

Degeneration of non-myelinated axons in the rat sciatic nerve following lysolecithin injection.

Lysolecithin has been used in many studies to induce demyelination in peripheral nerves. In the present investigation lysolecithin (lysophosphatidyl choline) was injected into rat sciatic nerves at a dose of 2-3 microns of a 10 mg/ml solution in order to study the effects of this lipid on cellular elements other than myelin within the nerve. Twenty-four hours after injection, there was splitting of myelin, lysis of Schwann cells, and complete loss of non-myelinated axons and their Schwann cells at the site of injection. Numerous swollen non-myelinated axons containing accumulated organelles were seen just proximal to the site of injection at 48 h. Loss of non-myelinated axons from the distal part of the nerve was also noted at 3 days after injection but 7 days regenerating non-myelinated axons had re-appeared in the distal part of the nerve. Although demyelination, followed by remyelination was prominent feature in the injected segment of the nerve, no damage to myelinated axons was detected. These results suggest that the presence of the myelin sheath protects the large myelinated axons against the action of lysolecithin, but with lysis of Schwann cells, the non-myelinated axons are exposed to the action of lysolecithin. Apart from selective damage to non-myelinated fibres with subsequent degeneration, it is also possible that lysolecithin interferes with axoplasmic flow in non-myelinated axons.

Animals↗
PubMed1982

Identity of ultrastructural effects of mercuric chloride and methyl mercury after intracerebral injection.

In man the clinical patterns of inorganic and organic mercury toxicity are different. Inorganic mercuric chloride mainly affects the renal and gastrointestinal systems. The characteristic neurological feature is a fine tremor, particularly of the hands and fingers. In contrast organic methyl mercury toxicity results in an exclusively neurological disorder, the characteristic features being ataxia, dysarthria, paresthesia and tunnel vision. To study the action of these classes of mercury compounds on neurones small amounts of mercuric chloride or methyl mercuric acetate were injected or iontophoresed into the rat cerebrum. The ultrastructural changes which followed were identical. Progressive and often pronounced cytoplasmic swelling of neurones suggested a defect at the cell membrane level. Thus is spite of their distinctive clinical syndromes these 2 classes of mercury compounds are capable of inducing neuronal necrosis.

Animals↗
PubMed1982

Similarities and differences on the MMPI between women with bulimia and women with alcohol or drug abuse problems.

This study compared the MMPI MacAndrew Scale, mean profile, mean scale scores, and codetypes of women with bulimia and women with alcohol or drug abuse problems. Women with alcohol or drug abuse problems scored significantly higher on the MacAndrew Scale and several mean MMPI scale scores than women with bulimia. However, mean MMPI profiles and distribution of MMPI codetypes were similar between these two groups.

Adolescent↗
PubMed1982

Transcriptionally active DNA region that rearranges frequently in murine lymphoid tumors.

A DNA region not associated with conventional immunoglobulin gene rearrangement is rearranged in many lymphoid tumors. This region, designated here as lymphoid rearranging (LyR) DNA, was cloned from plasmacytoma J558 in which it had recombined 5' to a constant (C) region of the alpha heavy (H) chain gene, C alpha, within a switch (S) region, S alpha, involved in the switching of CH genes. Sequence determination established that LyR DNA had recombined within a S alpha recombination unit. LyR DNA does not originate from the H chain locus, and discordance between LyR DNA and CH copy number in certain lines suggests that LyR DNA probably derives from another chromosome. LyR DNA rearrangement is a characteristic of tumors of mature B cells; it was detected in 24 of 28 plasmacytomas and B-cell lymphomas, usually as LyR-S alpha, but not in 11 Abelson retrovirus-induced lymphomas of B-cell precursors nor detectably in normal B cells. In contrast, rearrangement was observed in only 3 of 18 T-cell lymphomas, and none of seven nonlymphoid lines. Most tumor lines (49 of 52), whether lymphoid or not, contained a low level of polyadenylylated LyR transcript(s), but several new RNA species with differences in their 5' regions appeared in B-cell lines in which LyR DNA was rearranged, suggesting that rearrangement may activate a new promoter or mode of splicing. The results suggest that the LyR-S alpha rearrangement represents a translocation to chromosome 12 that alters expression of LyR-encoded genes; hence, it may have participated in lymphoid tumor oncogenesis.

Animals↗
PubMed1982

Flat small intestinal mucosa and autoantibodies against the gut epithelium.

A male infant, aged 1 year 3 months, was admitted to the hospital with protracted diarrhoea, vomiting, and weight loss. The diarrhoea and vomiting coincided with an outbreak of acute diarrhoea and vomiting affecting other family members. Biopsy showed a flat small intestinal mucosa which did not respond to a diet free of gluten, cow's milk, and eggs, or during 8 weeks of intravenous alimentation. Steroids were given, and courses of nalcrom and later cimetidine, but these did not produce any significant improvement. A rare IgG autoantibody specific for gut epithelium was found, which, when present, was associated with a cytological abnormality of crypt enteroblasts. The autoantibody disappeared after treatment with cyclophosphamide, and the cytological abnormality subsequently diminished. However, the mucosa remained severely abnormal and has been so for 23 months. It is possible that an autoimmune reaction against the patient's small intestinal mucosa has led to persistence of the enteropathy.

Animals↗
PubMed1982

Reproducibility of prick skin tests to five allergens.

Thirty-five patients had prick skin tests to the common allergens Candida albicans. Aspergillus fumigatus, grass pollen, horse dander and Dermatophagoides pteronyssinus performed on a regular basis from Autumn 1973 to Autumn 1975. Specific IgE to the same allergens (except C. albicans) was determined at the time of skin testing for the first five seasons. It was found that the position on the volar aspect of the forearm on which the test was performed did not affect the reaction. There was a significant variation in the percentage of patients with positive skin tests to A. fumigatus, grass pollen and horse dander with the latter showing as significant decrease with time. There was evidence of variation in weal size for all but C. albicans, and for grass pollen, horse dander and D. pteronyssinus there were reduction in weal size with time. Significant differences were found for results of Log specific IgE for grass pollen and D. pteronyssinus over the study, but there was no trend. A good correlation between weal size and Log specific IgE for grass pollens and D. pteronyssinus was observed. For the four allergens, the coefficient of concordance between IgE levels within patients for the five seasons was highly significant.

Allergens↗
PubMed1982

Role of the cervix in the induction of labor.

A study on induction of labor was carried out to test the hypothesis that changing the cervix will enhance the effectiveness of induction of labor. Fifty pregnant women near term with Bishop scores of 4 or less were divided into 5 study groups, in which a 12-hour preparation phase procedure was carried out to produce cervical or myometrial changes. All women had continuous measurement of uterine activity by an extraovular catheter. The patients were divided into 1) control subjects, and into groups treated with 2) laminaria, 3) Foley catheter, 4) amniotomy, and 5) oxytocin infusion. These preparation techniques were used for 12 hours, after which rupture of membranes was carried out in all cases. Although all procedures significantly changed the cervix, none but oxytocin affected the induction-to-delivery interval. The authors concluded that when a study design rigidly controls for cervical Bishop score, timing of rupture of membranes, and oxytocin infusion rates, the cervical preparation alone will not enhance inducibility.

Amnion↗
PubMed1981

Cerebral ventriculitis in the hydrocephalic mouse: a histological and scanning electron microscope study.

Staphylococci are the commonest organisms found in infected cerebrospinal fluid shunts in hydrocephalic patients. In the present study, staphylococcus albus was injected (1200-500,000 organisms in 10 microliters saline) into the ventricles of the hydrocephalic mouse SUMS - hy - 3/+ (temporary strain name). The bacteria appeared to have little direct effect upon the ependymal cells lining the ventricles and were not found as free organisms in the subependymal tissue. Staphylococci were phagocytosed by polymorphonuclear leukocytes which entered the ventricle from the choroid plexus and through the ependyma from subependymal vessels. Macrophages on the lining of the hydrocephalic ventricles also played a significant role in the phagocytosis of bacteria in the early stages of infection.

Animals↗
PubMed1981

The catecholaminergic nerve supply to small intracerebral vessels following a cold injury to the mouse cortex.

A cold lesion was produced in the mouse parietal cortex. The damaged area was examined for alterations in the catecholamine fibres either by fluorescence microscopy or by electron microscopy. Within 24 h of injury many damaged catecholaminergic nerves were observed in close association with small intracerebral blood vessels. This relationship between nerves and blood vessels was not apparent in the control cortex. In the electron microscope, swollen non-myelinated axons containing an accumulation of dense-cored vesicles were observed close to the vessel wall but separated from it by astrocytic process. Six days after injury regenerating catecholaminergic nerve fibres were found close to immature capillaries. Axonal-like profiles containing dense-cored vesicles were observed adjacent to the endothelial call basement membrane. The number of regenerating nerves declined with time and the only fluorescent catecholaminergic nerves that remained 12 weeks after injury were in an area known to be rich in capillaries.

Animals↗
PubMed1981

The uptake and retrograde transport of horseradish peroxidase--polylysine conjugate by ligated postganglionic sympathetic nerves in vitro.

The uptake and retrograde transport of horseradish peroxidase (HRP) and horseradish peroxidase-poly-L-lysine conjugate (HRP-PL) were compared using a system comprising the guinea-pig inferior mesenteric ganglion (IMG) and ligated hypogastric hypogastric nerves maintained in vitro in a twin chamber apparatus. 0.5 mg of HRP-PL applied to the ligated nerves produced stronger retrograde labelling of neurons within the IMG than did 10 mg of HRP. This may have been due to the greater uptake of HRP-PL in a vesicular form by the axons immediately proximal to the ligation. The possible roles of large rounded vesicles and elongated cisternae in retrograde axoplasmic transport are discussed.

Animals↗
PubMed1981

A morphological study of the uptake and orthograde axoplasmic transport of horseradish peroxidase by damaged autonomic neurons in vitro.

A preparation comprising the guinea-pig inferior mesenteric ganglion (IMG) and ligated hypogastric nerves was maintained in vitro in a twin-chamber apparatus. Horseradish peroxidase (HRP), added to the ganglion compartment, was taken up via coated pinocytotic vesicles into the neuronal perikarya, and subsequently accumulated in many polymorphic cytoplasmic organelles, but it did not enter the Golgi complex. After 24 h incubation, HRP was also localized in membrane-bounded organelles in the nonmyelinated axons of the hypogastric nerves in the ligated nerve compartment. HRP-labelled organelles accumulated in swollen nonmyelinated axons immediately proximal to the ligation along with other organelles known to undergo fast axoplasmic transport. It is suggested that HRP taken up by the neuronal perikarya subsequently underwent fast axoplasmic transport without passing through the Golgi complex. The organelles in which HRP was transported in an orthograde direction were very similar to those in which the enzyme is known to be transported retrogradely in the same neuronal system. The advantages of this in vitro system for studying the orthograde transport of exogenous protein are discussed.

Animals↗
PubMed1981

Methemoglobinemia from isobutyl nitrite preparations.

Ingestion of preparations containing isobutyl nitrite can lead to rapidly fatal methemoglobinemia. We report the cases of three patients presenting with methemoglobinemia secondary to ingestion or inhaling the contents of an over-the-counter room odorizer preparation containing isobutyl nitrite. The condition was treated successfully with administration of intravenous methylene blue.

Adolescent↗
PubMed1981

On the mechanism of the uptake of horseradish peroxidase into the retrograde transport system of ligated postganglionic sympathetic nerves in vitro.

The mechanism of the uptake of horseradish peroxidase (HRP) by damaged post-ganglionic sympathetic axons was studied in vitro. HRP was applied to the damaged axons at the time of nerve injury or after a 3 hours or 17 hours delay. An interval of 3 hours or 17 hours between nerve injury and exposure to HRP had no effect on the localisation of the HRP in the damaged axons or on its retrograde transport to their perikarya. Evidence was found for the pinocytotic uptake of the enzyme by the damaged axons and its accumulation within those axons in elongated cisternae and larger rounded vesicles. In further experiments the damaged axons were treated with HRP at 0 degrees C and then washed in HRP-free medium. The tracer entered the axons in a diffuse form under these conditions but no pinocytotic uptake was observed. However, following 24 hours further incubation at 37 degrees C, HRP could not be found in the perikarya. Treatment at 0 degrees C did not produce any lasting damage to the retrograde transport mechanism. The results of these experiments are compatible with the involvement of pinocytosis in the uptake of HRP in a form suitable for retrograde transport.

Animals↗
PubMed1981

Propiram and codeine in episiotomy pain.

To evaluate relative efficacy, safety, and time course of analgesia, propiram fumarate (50 and 100 mg), a new narcotic agonist-antagonist, was compared with codeine sulfate (60 mg) and placebo in a clinical trial with a single peroral dose, parallel, stratified, randomized, and double-blind design involving 80 hospitalized postpartum women with medium or severe episiotomy pain. Using verbal subjective reports as index of response, patients rated pain intensity and side effects at periodic interviews for 6 h. Relative efficacy findings based on peak effects and summed pain-intensity differences suggested dose-dependent analgesia with propiram and also that 60 mg codeine lay between 50 mg propiram and placebo. Moreover, after 50 or 100 mg propiram, 8 of 20 patients reported greater than 50% reduction of initial pain compared with 7 of 20 after 60 mg codeine and 2 of 20 after placebo. After each of the propiram doses, distinct analgesia began within 1/2 h and reached peak effect between 1 h (p less than 0.02) and 2 h (p less than 0.05). After f60 mg codeine, onset was slower and peak later (4 h, p less than 0.05). All three active drugs continued to act until the 5th or 6th h. Drowsiness was the only statistically significant side effect reported after propiram. These results suggest that single 50 or 100 mg doses of propiram were effective in episiotomy pain, induced stronger analgesia than 60 mg codeine, and took effect more rapidly.

Analgesics↗
PubMed1981

The origin of the preganglionic parasympathetic fibres to the mandibular and sublingual salivary glands in the rat: a horseradish peroxidase study.

Horseradish peroxidase was applied to a ligation of the chorda tympani nerves running alongside the submandibular duct in order to label the preganglionic parasympathetic salivatory neurons in the brain stem. Labelled neurons were found in the ipsilateral motor trigeminal nucleus, lateral reticular formation and in the facial motor nuclei of both sides. However, the labelling of neurons in the motor nuclei of the trigeminal and facial nucleus was caused by the uptake of horseradish peroxidase by axons in the musculature surrounding the injection site which were probably damaged by the dissection procedure. The salivatory neurons were fusiform multipolar cells which were mainly located in the ipsilateral nucleus reticularis parvocellularis. No evidence for salivatory neurons in the nucleus supragenualis was found.

Animals↗