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Biomedical subjects

S Kahn

Publications and source records attributed to S Kahn.

At least 73 records · Page 4Linked to original sources
PubMed1987

Revised post-mortem inspection procedures for cattle and pigs slaughtered at Australian abattoirs.

Revised procedures for the post-mortem inspection of cattle and pigs at Australian abattoirs were developed as minimum national requirements. Comparative trials of current and revised procedures were conducted at 3 and 4 Australian abattoirs for pigs and cattle respectively. Residual pathological changes after inspection and removal of lesions from heads, carcases or viscera were recorded by an evaluation team with the data used to determine relative effectiveness. For cattle, there was no significant difference between current and revised procedures. Although it had been proposed to eliminate routine incision of cervical lymph nodes for pigs, it was found necessary to retain this procedure. The data also revealed a significant variation in detection of pathology between abattoirs for both species. Parasitic conditions accounted for the greatest proportion of undetected lesions in both species for both current and revised procedures. These comprised mainly fascioliasis in cattle and ascariasis in pigs. The former was associated with the study being conducted in eastern Australia. Chronic interstitial nephritis was also a common undetected lesion, reinforcing the need for intensified inspection of kidneys. However, such residual pathology was considered to be of only limited significance to human health. The revised procedures and findings are discussed in the context of animal and human health and of the importance of the meat industry to Australian exports. Some attention has been given to specific conditions likely to be affected by the proposals including tuberculosis, bovine cysticercosis, fascioliasis, porcine arthritis and salmonellosis. The role of meat inspection in monitoring for specific diseases is discussed.(ABSTRACT TRUNCATED AT 250 WORDS)

Abattoirs↗
PubMed1986

Biochemical and immunocytochemical evidence for a deficiency of normal interfascicular oligodendroglia in the CNS of the dysmyelinating mutant (md) rat.

Carbonic anhydrase was assayed and carbonic anhydrase and 5'-nucleotidase were localized in the CNS of myelin-deficient mutant rats and normal littermates. The carbonic anhydrase specific activities were reduced by 61% and 29% in the mutants' forebrains and cerebella, respectively, and the total carbonic anhydrase activity in the spinal cords was reduced by 35%. Immunostained cells were found in gray matter from both normal and mutant rats, but, in the mutants, there was a marked deficiency of interfascicular oligodendrocytes in the regions that are normally occupied by white matter. It is suggested that a developmental study could indicate the step(s) at which normal differentiation of interfascicular oligodendroglia is blocked in this mutant.

5'-Nucleotidase↗
PubMed1985

Oligodendroglial structures and distribution shown by carbonic anhydrase immunostaining in the spinal cords of developing normal and shiverer mice.

The spinal cords of young and adult normal and dysmyelinating mutant (shiverer) mice were immunostained with anticarbonic anhydrase to investigate the distribution of oligodendroglial populations into the gray- and white-matter regions in the developing normal and mutant animals; the morphology of oligodendrocytes and their processes at the light microscopic level in gray matter and white matter; and the apparent gliosis in the gray matter, as well as the white matter, of the mutants. Immunocytochemistry and enzyme assays revealed consistent increases in carbonic anhydrase antigenicity and specific activity in controls and mutants between the ages of approximately 15 days and approximately 60 days. As shown previously in adult animals, oligodendroglia in larger than normal proportions were situated at the periphery of the "white-matter" columns, as compared to gray matter, in the shiverers, with, however, significant numbers of oligodendroglia were heterogeneous with respect to shapes, configuration of processes, and intensity of carbonic anhydrase immunostaining. In the shiverer "white matter" the oligodendrocytes were smaller than normal, and their shapes and arrangement were relatively irregular. In the normal gray matter short oligodendroglial processes appeared to be associated with neuronal perikarya, and those processes were more pronounced at approximately 90 days than at approximately 20 days of age. Background staining in normal gray matter suggested that oligodendroglial processes were, in addition, tightly wound around many axons. In shiverer gray matter the oligodendrocytes were smaller, and their processes appeared to be wrapped more loosely around smaller numbers of conspicuous axons and to be associated less frequently with neuronal perikarya. This finding suggests that the deficiency in the myelin basic protein in the mutant may affect interactions between oligodendrocytes and neurons in the gray matter as well as in the white matter. The astrocytic "marker," glial fibrillary acidic protein, was detected in gray and white matter of shiverers as young as 16 days, and the differences from carbonic anhydrase localization supported the conclusion that the processes enwrapping axons in the shiverer mouse CNS are derived from oligodendrocytes, not astrocytes.

Age Factors↗
PubMed1985

Immunocytochemical localization of 5'-nucleotidase in oligodendroglia and myelinated fibers in the central nervous system of adult and young rats.

Rat central nervous system (CNS) tissue sections were immunostained by the peroxidase-anti-peroxidase (PAP) method using a rabbit serum directed against rat liver 5'-nucleotidase. In paraffin sections from the brains of 60-day-old rats 5'-nucleotidase immunoreactivity occurred in the same white-matter regions as myelin-basic protein immunoreactivity and histological staining of myelin. The immunostaining of cerebral white matter for 5'-nucleotidase was more intense and wide-spread at the age of 120 days than at 60 days, and the choroid plexus and blood vessels were stained consistently. In the paraffin sections from the brains of younger (20-day-old) rats the staining of 5'-nucleotidase in the white matter was faint and patchy. In paraffin sections from spinal cord, 5'-nucleotidase immunoreactivity was observed throughout the lateral white-matter columns and, frequently, in the cell bodies of interfascicular oligodendroglia. Interfascicular oligodendroglia also showed 5'-nucleotidase immunoreactivity in vibratome sections from the CNS tissue of young and adult rats. The findings were consistent with histochemical and biochemical evidence for 5'-nucleotidase in rat brain myelin and oligodendroglia, with substantial increases in activity in the myelin as rats develop from the ages of 20 to 120 days. 5'-Nucleotidase immunoreactivity was not observed in any astrocytes or in oligodendrocytes in the gray matter; however, the enzyme may occur in those glial cells at levels lower than were detectable using the present method.

5'-Nucleotidase↗
PubMed1984

Biochemical abnormalities in spinal cord myelin and CNS homogenates in heterozygotes affected by the shiverer mutation.

Myelin was purified from the spinal cords of normal mice and mice heterozygous for the shiverer mutation, and measurements were made of the major myelin proteins and lipids and the specific activities of three myelin-associated enzymes. The myelin purified from the spinal cords of the heterozygotes (shi/+) was deficient by 30-40% in yield and had an apparently unique composition. In particular, when compared with normal mouse spinal cord myelin, there were more high-molecular-weight protein, less myelin basic protein, a higher protein-to-lipid ratio, and higher specific activities of 2',3'-cyclic nucleotide-3'-phosphohydrolase (EC 3.1.4.37) and carbonic anhydrase (EC 4.2.1.1) in the myelin purified from the shi/+ animals. These abnormalities were reflected in the composition of shi/+ whole spinal cord, where the protein-to-lipid ratio was intermediate between the respective values for +/+ and shi/shi spinal cords. Whole brains from shi/+ mice showed deficiencies in galactocerebroside and galactocerebroside sulfate and an increase in total phospholipid, and the lipid composition in the brains of the shi/shi mice was similar to that reported for another dysmyelinating mutant, quaking. The findings provide the first values for the lipids in normal mouse spinal cord myelin and show that heterozygotes are affected by the shiverer mutation. The observations imply that there can be considerable deviation from the normal CNS myelin content and composition without apparent qualitative morphological abnormalities or loss of function and that the amount of myelin basic protein available during myelination may influence the incorporation of other constituents into the myelin membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Nucleotide sequence of the long terminal repeat and flanking cellular sequences of avian endogenous retrovirus ev-2: variation in Rous-associated virus-0 expression cannot be explained by differences in primary sequence.

A fragment of chicken DNA containing the left long terminal repeat of endogenous retrovirus ev-2 and flanking cellular sequences has been molecularly cloned and analyzed. Comparison with sequence data from the analogous regions of ev-1 and Rous-associated virus-0 viral DNA reveals similarities among flanking regions of the integrated proviruses and among all three long terminal repeats. From the latter finding, we conclude that the difference in level of expression of ev-2 and its progeny Rous-associated virus-0 provirus cannot be due to sequence differences in their upstream long terminal repeats.

Animals↗
PubMed1983

Comparison of Intralipid 10% and Intralipid 20% as a source of energy and essential fatty acids--a multicenter study.

A multicenter clinical study was done which directly compared efficacy and safety of Intralipid 10% and Intralipid 20%. Twenty-nine patients received the 10% concentration, 30 patients received the 20% concentration. Both groups of patients received equivalent amounts of calories, amino acids, dextrose and fat for seven day study periods. Analysis of nitrogen balance data showed that the two preparations were equally effective in maintaining nitrogen balance. Both concentrations of fat emulsion were effective in reversing or correcting the changes of essential fatty acid deficiency. Analysis of clinical laboratory data indicated that both preparations were equally well tolerated by the patients. No adverse effects attributed to the fat emulsions were observed.

Adult↗
PubMed1979

Alternatives to subcutaneous mastectomy.

It is our belief that subcutaneous mastectomy often leads to complications, with poor results. In addition, because a considerable amount of breast tissue may be left behind, its value as a prophylactic operation must be questioned. Two alternatives are presented. In our experience, these lead to fewer complications with a more thorough removal of the mammary gland, and achieve a better appearance. The alternatives are (1) simple mastectomy with secondary reconstruction; (2) the type of mastectomy described by Spira--with primary reconstruction using a subpectoral silicone prosthesis covered by muscle and an inferiorly-based dermal flap.

Adenofibroma↗
PubMed1978

Case 22, part 1.

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Adult↗