Search PubMed⌕ Search

Biomedical subjects

J G Hall

Publications and source records attributed to J G Hall.

At least 217 records · Page 12Linked to original sources
PubMed1984

The transfer of immune complexes from the lumen of the small intestine to the bloodstream in sucking rats.

The epithelial cells along the small intestine of the sucking rat display specific receptors for IgG. These permit the uptake and transcellular transport of IgG, usually presented in milk, from the gut to the bloodstream. Antigen already combined with IgG may also gain access to the bloodstream by this route, but no data exists to show whether this could be sufficient to immunize or to induce tolerance in the young rat to a future exposure to antigen. Monoclonal IgG1 antibody to horseradish peroxidase was used in order to quantitate such a transfer of antigen, using the electron microscope and also studies with radiolabelled antigen and/or antibody. It was found that much less intact antigen was transferred to the bloodstream than would have been calculated from the quantity of antibody transported. Also, IgG1 combined with antigen was more likely to be broken down intracellularly than free IgG1. This was compared with the transport across rat hepatocytes of monoclonal polymeric IgA anti-horseradish peroxidase. The transfer of polymeric IgA from blood to bile was the same whether or not the IgA was complexed with antigen. However, as for the IgG system, less antigen was transported intact into bile than might have been expected theoretically.

Animals↗
PubMed1984

An approach to research on congenital contractures.

We have described a study evaluating over 1,500 patients said to have arthrogryposis. It is clear that arthrogryposis is a sign and not a diagnosis. The approach was one of collecting information and sorting out specific groups of patients. We employed a flexible protocol that allowed us to go back and collect additional information from families. Our study was pared down to include 350 patients, who were studied in detail. A great deal of heterogeneity exists within what has been called arthrogryposis. We have developed an approach to patients with congenital contractures, which is to divide them into three groups, depending on whether they have primarily limb involvement, whether they have limb involvement plus other abnormalities, or whether they have limb involvement plus CNS dysfunction. In this manner, we arrived at a useful differential diagnosis for each of these categories. We have been able to recognize not only a number of specific entities, but also principles of therapies. The approach has allowed us to say something about recurrence risks, natural history, and also which treatment is most appropriate for an individual case. It would appear that our interest in, and study of congenital contractures, have also led to a better understanding of the factors involved in normal development of joints. This has occurred by accumulating a large group of patients and evaluating each of them systematically.

Arthrogryposis↗
PubMed1984

Diagnostic considerations in arthrogryposis syndromes in South Africa.

Congenital rigidity of multiple joints poses a difficult diagnostic and therapeutic problem. There are also semantic difficulties as the non-specific term "arthrogryposis" is often used for any individual with congenital limitation of joint movement. Many distinct syndromes present in this way and as they differ in their course, prognosis and genetic implications, diagnostic precision is crucial. A diagnostic analysis is given of 247 South African patients in whom "arthrogryposis" had been recorded, and the pathogenesis and nosology of congenital contractures are discussed in this paper. Three of these stiff joint conditions were originally described in South African patients, i.e. Liebenberg synostosis syndrome, digitotalar dysmorphism, and the Gordon syndrome of autosomal dominant cleft palate, camptodactyly and club feet.

Arthrogryposis↗
PubMed1984

The flow and composition of lymph from the caudal mediastinal lymph node of sheep.

By cannulating the efferent duct of the caudal mediastinal lymph node in sheep, lymph from the lower respiratory tract was collected under physiological conditions for several days. In 18 such preparations the flow rate varied from 4 to 12 ml/hr between individuals and the lymphocyte count between 4000 and 117,000/mm3. The protein content of the lymph plasma averaged nearly 60% of that of the blood, and this indication of the high permeability of the capillary bed of the lungs was confirmed by measuring the time taken for intravenous doses of 125I-albumin to equilibrate between the blood and mediastinal lymph plasma. The concentration of immunoglobulin A was higher in the mediastinal lymph than in blood serum, while the reverse was true of the concentrations of IgG1, IgG2, and IgM. This evidence for the local production of IgA by the intra thoracic lymphoid tissue was supported by the demonstration by immunoperoxidase techniques of IgA-containing plasma cells in sections cut from the caudal mediastinal nodes, and of IgA-containing immunoblasts in the lymph.

Animals↗
PubMed1983

Cytogenetic findings in over 2000 amniocenteses.

Between 1971 and 1981, 58 (2.8%) of 2037 amniocenteses performed in Vancouver revealed chromosome abnormalities, 25 of which were trisomy 21. Of the 58 referrals that yielded abnormalities, 37 (63.8%) were for a maternal age of 38 years or more. The rates of detection of such abnormalities for single-year intervals of maternal age beyond 35 years were comparable to those calculated from pooled data obtained in multicentre studies in the United States, Canada and Europe.

Amniocentesis↗
PubMed1983

Part I. Amyoplasia: a common, sporadic condition with congenital contractures.

A specific congenital contracture (arthrogryposis) syndrome has been recognized in 135 out of 350 patients with various kinds of congenital contractures. This sporadic syndrome, designated amyoplasia is characterized by absence of limb muscles that are replaced by fibrous and fatty tissue. At birth there is characteristic positioning of the limbs with internal rotation at shoulders, extension at elbows, and flexion of the hands at the wrists. Severe equinovarus deformities of the feet are usually present. Contractures at knees and hips occur in a variety of positions. Typically, the face is round with a frontal midline capillary hemangioma and slightly small jaw. Intelligence is normal. Approximately 63% of our patients had involvement of four limbs (almost always symmetrically), 24% mainly of lower limbs, and 13% mainly upper limbs. Typically, no other malformations are present. However, minor anomalies are seen often, and include hypoplastic digits and hypoplasia of scrotum or labia, the umbilical cord may be wrapped about a limb at birth. In utero fetal activity is decreased and breech delivery is increased in amyoplasia. All cases were sporadic; identical twins are discordantly affected.

Adolescent↗
PubMed1983

Part II. Amyoplasia: twinning in amyoplasia--a specific type of arthrogryposis with an apparent excess of discordantly affected identical twins.

We report on 11 cases of amyoplasia in one of identical twins. In total, 135 patients with amyoplasia were ascertained from a study of 350 patients with multiple congenital joint contractures (arthrogryposis). These 11 cases of identical twins with amyoplasia represent 8% of our patients with amyoplasia. At least 18 sets of twins with congenital contractures have been reported previously. However, only four of these appear to involve identical twins discordant for amyoplasia. Thus, 15 cases in which only one of identical twins are affected with amyoplasia have been identified.

Adolescent↗
PubMed1983

Neuropathologic findings in the spinal cords of 10 infants with arthrogryposis.

The lumbosacral cord segments of 10 infants with varying clinical forms of neurogenic arthrogryposis were compared with similar spinal cord segments from an infant with congenital contractures secondary to uterine constraint, 8 infants with Werdnig-Hoffman syndrome, and 11 age-matched controls. Neuronal numbers, sizes, and distribution were measured within the anterior horns. In addition to the classical reduction in the numbers of alpha motor neurons in both pathologic states, this study found the smaller neurons of the anterior horn were absent or diminished in Werdnig-Hoffman syndrome, while those cells were present in increased numbers with abnormal histology in all the patients with arthrogryposis. In 5 of the patients with arthrogryposis, the pathologic pattern was consistent throughout each cord segment; in 5 others, normal alpha neurons were retained and unequally distributed in the anterior horn segments. This unequal distribution predicted the muscle group involvement and suggested the mechanism for intrauterine joint fixation in these patients. The pathologic changes in the patients with arthrogryposis appear to be unique in spite of the heterogeneity of etiology and the clinical presentation.

Anterior Horn Cells↗
PubMed1983

Effect of alcohol on the integrity of the intestinal epithelium.

The absorption of macromolecules from the small intestine of rats was studied in terms of the amount of peroxidase activity that appeared in thoracic duct lymph after a 10 mg dose of horseradish peroxidase had been injected directly into the lumen of the duodenum. When the horseradish peroxidase was injected as a solution in saline no peroxidase activity was detected in the lymph. When ethyl alcohol was included in the dose at final concentrations of 12.5-16% the flow rate of the lymph increased markedly for an hour or so and during this time peroxidase activity was detected in the lymph. An electronmicroscope study of the duodenal epithelium that had been exposed to alcoholic solutions of horseradish peroxidase showed that the enzyme had penetrated between the enterocytes. It was concluded that the presence in the intestine of substantial amounts of alcohol temporarily destabilises the intercellular junctions of the epithelium and thus promotes the absorption of materials which are normally excluded.

Animals↗
PubMed1983

The occurrence of secretory IgM in the bile of rats.

The concentration of IgM in the bile of normal rats is extremely small, too low to be detected by conventional immunodiffusion methods. However, IgM is easily detected in bile samples from rats bearing the IgM secreting IR202 plasmacytoma, at concentrations ranging from 0.07 to 1.2 mg/ml. The IgA concentration in the same bile samples is about half the normal level, whereas in corresponding samples of serum, IgA concentrations are elevated by a factor of three. Most of the IgM in the bile is complexed with secretory component. Thus, when IgM concentrations in the blood are sufficiently high relative to those of IgA, IgM in rats is capable of undergoing transhepatic transport by the same route as polymeric IgA. This situation probably corresponds to that in IgA deficient humans where IgM replaces polymeric IgA in the secretions.

Animals↗
PubMed1983

IgA antibodies in the bile of rats. III. The role of intrathoracic lymph nodes and the migration pattern of their blast cells.

Eight weeks after rats had had their mesenteric lymph nodes (MLN) removed surgically, they were found to be still able to generate substantial titres of biliary IgA-antibodies after antigens were injected into their Peyer's patches. This suggested that systemically significant IgA production could be induced in extra-abdominal lymphoid tissue. It was found that the intrathoracic lymph nodes (ITLN) were an important source of IgA production. These nodes could be stimulated to produce biliary antibody by introducing antigen either into the peritoneal cavity or directly into the thorax. Cells forming IgA were identified in the ITLNs by haemolytic plaque assays and immunoperoxidase techniques. In spite of this, immunoblasts obtained from the ITLNs, and labelled with 125IUdR did not localize in the gut after i.v. injection to anywhere near the extent that immunoblasts from the MLN did. Instead they seemed to have a predilection for localizing in the lungs.

Animals↗
PubMed1982

The location of brainstem neurones tonically inhibiting dorsal horn neurones of the cat.

In an investigation of the origin of tonic descending inhibition of dorsal horn neurones by impulses in unmyelinated primary afferents, brainstem regions were electrolytically lesioned. With each neurone studied, tonic descending inhibition was measured before and after brainstem lesions by cooling a segment of spinal cord cephalic to the recording site. Such inhibition was not reduced by lesions of areas which, when stimulated, produce analgesia. These included the periaqueductal grey and the raphé areas of the midbrain and pons-medulla. Tonic descending inhibition was reduced by bilateral lesions of the ventrolateral caudal medulla in the region of the lateral reticular nuclei. Lateral reticular areas may have a functional role in the control of pain.

Afferent Pathways↗