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Biomedical subjects

B Kohn

Publications and source records attributed to B Kohn.

At least 37 records · Page 2Linked to original sources
PubMed1995

[Neoplasms originating from large granular lymphocytes in a dog and cats].

Clinical, cytological and pathological findings in three cases of large granular lymphoma in a dog and two cats are presented. These tumors consist of large granular lymphocytes, which have been in part classified as natural killer cells, based on their phenotype and functional aspects. It is likely that such tumors are more frequent than commonly appreciated, because they are only recognized as such in cytological preparations or in electron microscopy.

Animals↗
PubMed1994

Zoo animal welfare.

The history of zoo animal welfare legislation extends back to 1876, and is often tied to general animal welfare regulations. As knowledge and societal values have changed, so have the focus of zoos and the regulations governing them. Today, the issues involved in zoo animal welfare are complex and broad-based. Building on the basic welfare tenets of adequate feed, water, shelter, sanitation and veterinary care, current issues include the following: handling and training of captive animals, psychological well-being and environmental enrichment, enclosure design, species preservation, environmental and conservation issues, captive-breeding programmes. Complicating the matter further, government regulations try to assimilate all aspects of zoo animal welfare into the laws to provide humane care and handling for all species concerned. Zoo animal welfare will remain a challenging area, as increasing demands are placed on zoos and regulatory agencies to manage this diminishing resource.

Animal Husbandry↗
PubMed1993

[Muscular dystrophy in a cat].

A case of muscular dystrophy in a 1-year-old male castrated Domestic Shorthair cat is presented. The most striking clinical features were regurgitation, a stiff gait, an increased muscle tone and exercise intolerance. Serum biochemistry panels showed a marked increase in the muscle specific enzyme creatine kinase, and moderately elevated levels of LDH, AST and ALT. Spontaneous electrical activity of skeletal muscles in the form of "bizarre high frequency discharges" and "myotonia-like repetitive discharges" were registered. Gross pathology revealed a marked hypertrophy of the skeletal muscles. The main histopathological changes were myofiber necrosis and calcification, variation in fiber size, hypertrophied muscle fibers of type I and type II and fiber splitting. Indirect immunofluorescence showed dystrophin deficiency. Feline muscular dystrophy resembles the X-linked human Duchenne muscular dystrophy (DMD). Besides the X-linked muscular dystrophy in the mouse and Golden Retriever the feline muscular dystrophy could represent another valuable animal model for the study of DMD.

Alanine Transaminase↗
PubMed1991

Osteopenia caused by ovariectomy in young female rats and prophylactic effects of 1,25-dihydroxyvitamin D3.

Young female rats were subjected to either bilateral ovariectomy or sham operation. One group of ovariectomized (ovx) animals was treated with the vitamin D metabolite 1,25(OH)2D3 after surgery. The effects of ovariectomy and 1,25(OH)2D3 treatment on different markers of bone formation (serum alkaline phosphatase, serum bone gla protein) and bone resorption (fasting urinary hydroxyproline) were determined. All rats were euthanized at 7 weeks post ovariectomy and their first lumbar vertebra were processed undecalcified for quantitative bone histomorphometry. A significant decrease in cancellous bone mass was noted in ovx compared with sham-operated rats. This bone loss was associated with increased biochemical markers of bone formation and bone resorption. Furthermore, ovariectomy led to elevated osteoblast perimeter and osteoid parameters as well as an increased osteoclast number. These data indicate that young growing rats develop osteopenia 7 weeks after ovariectomy which goes along with an accelerated bone turnover. Bone gla-protein, alkaline phosphatase and hydroxyproline can be useful markers in studies with ovx rats. Treatment with 1,25(OH)2D3 led to a lowered urinary hydroxyproline excretion and a significant decrease of osteoclast number whereas histomorphometrical indices of bone formation were nearly unchanged. Cancellous bone mass increased significantly in ovx rats treated with 1,25(OH)2D3 compared with non-treated rats. These results suggest that 1,25(OH)2D3 has a prophylactic effect with regard to bone loss in ovx rats which refers to a diminished bone resorption in the high bone turnover condition of ovx animals.

Animals↗
PubMed1990

Role of vitamin D metabolites in the prevention of the osteopenia induced by ovariectomy in the axial and appendicular skeleton of the rat.

Forty Fischer-344 rats (10 weeks old, 130 g BW) were either bilaterally ovariectomized (OVX) or sham-operated (SHAM). The rats were allocated to the following groups: SHAM; OVX; OVX + 15 ng 1 alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3]/rat/d; OVX + 30 ng 1 alpha,24R,25-trihydroxyvitamin D3 [1,24,25(OH)3D3]/rat/d; OVX + 15 ng 1,25(OH)2D3/rat/d + 30 ng 1,24,25(OH)3D3/rat/d. The vitamin D metabolites were fed orally starting 4 weeks after surgery. Urine and blood samples were taken at several time points during the experiment. Twenty-one weeks after surgery all rats were sacrificed, and the proximal tibiae and the first lumbar vertebrae were processed undecalcified for static bone histomorphometry. Ovariectomy induced a 40% reduction in vertebral cancellous bone area, and a 69% reduction in tibial cancellous bone area. This bone loss in OVX rats was associated with moderately increased biochemical and histomorphometric indices of bone formation and resorption as compared to values in sham-operated animals. Through inhibition of bone resorption, treatment of OVX rats with 1,25(OH)2D3, 1,24,25(OH)3D3, and the metabolite combination prevented the ovariectomy-induced osteopenia in the lumbar vertebra, and partially prevented cancellous bone osteopenia in the tibial metaphysis. However, OVX rats receiving 1,25(OH)2D3 alone or in combination with 1,24,25(OH)3D3 exhibited hypercalcemia, hyperphosphatemia, hypercalciuria, and impaired bone mineralization. Treatment of OVX rats with 1,24,25(OH)3D3 alone, on the other hand, only slightly increased serum calcium levels and did not impair bone mineralization. Furthermore, the inclusion of 1,24,25(OH)3D3 with 1,25(OH)2D3 partially antagonized the untoward effects of 1,25(OH)2D3 on bone mineralization. These data suggest that the actions of 1,24,25(OH)3D3 on bone metabolism might differ from that of 1,25(OH)2D3, and that 1,25(OH)2D3 and, particularly, 1,24,25(OH)3D3 may be potentially effective agents for the prophylaxis of postmenopausal osteoporosis.

24,25-Dihydroxyvitamin D 3↗
PubMed1990

Histomorphometric analysis of the rat proximal tibial metaphysis by "linear scanning".

Twenty-four female Sprague-Dawley rats (10 weeks old, 200g BW) were either sham-operated (n = 6) or ovariectomized (ovx). Ovx rats were divided into 3 groups (n = 6 each): ovx; ovx + 1,25-(OH)2D3; ovx + 1,25(OH)2D3 + 1,24,25-(OH)3D3. The vitamin D metabolites were fed orally starting the day after surgery. After 7 weeks all rats were sacrificed and the proximal tibiae were processed undecalcified for quantitative histomorphometry. Conventional histomorphometric analysis of the distal zone (greater than 1 mm from the growth cartilage) of the tibial metaphysis revealed a dramatic loss of cancellous bone mass in ovx rats. Both 1,25(OH)2D3 and the combination of 1,25(OH)2D3 with 1,24,25(OH)3D3 prevented the bone loss in the distal zone in ovx animals. Measurements in the proximal zone (less than 1 mm from the growth cartilage) of the tibial metaphysis were performed with a newly developed technique that utilizes the advantages of automatic image analysis, and that we propose to name "linear scanning". This method revealed a significantly decreased hard tissue mass at about 100 microns and within 800 to 950 microns distance from the growth plate in ovx rats. However, ovx rats reached normal amounts of hard tissue within 250 to 450 microns from the growth plate. The results obtained by linear scanning suggest that the obvious loss of cancellous bone mass in the distal zone of the tibial metaphysis in growing ovx rats is not a consequence of structural changes in the proximal zone.

24,25-Dihydroxyvitamin D 3↗
PubMed1983

Genotyping steroid 21-hydroxylase deficiency: hormonal reference data.

Hormonal reference data, in the form of nomograms relating baseline and stimulated levels of adrenal hormones, provide a means of genotyping steroid 21-hydroxylase (21-OH) deficiency in congenital adrenal hyperplasia. Data from both 360- and 60-min ACTH stimulation tests are given. The serum hormone concentrations that have proven most useful in classifying 21-OH deficiency are 17-hydroxyprogesterone and delta 4-androstenedione. These nomograms clearly distinguish the patient with classical 21-OH deficiency from those with the milder symptomatic and asymptomatic nonclassical forms of 21-OH deficiency (previously referred to as late onset and cryptic forms) as well as heterozygotes for all of the forms and those subjects predicted by HLA genotyping to be unaffected. The nomograms also can identify individuals heterozygous for 21-OH deficiency in the general population who have a characteristic heterozygote response. These nomograms provide a powerful tool by which to assign the 21-OH deficiency genotype. Patients whose hormonal values fall on the regression line within a defined group are assigned to that group. In view of the strong correlation between the 60- and 360-min ACTH stimulation tests, the less cumbersome and shorter 60-min test can be used with the same confidence as the longer test.

Adrenal Hyperplasia, Congenital↗
PubMed1982

Late-onset steroid 21-hydroxylase deficiency: a variant of classical congenital adrenal hyperplasia.

Hormonal studies and human leukocyte antigen (HLA) genotyping were performed in 5 males and 13 females who were demonstrated to have 21-hydroxylase deficiency. The enzymatic deficiency of steroidogenesis was detected by family studies of 10 females who presented with varying symptoms of androgen excess. The 10 index cases had normal genitalia at birth, but virilized to varying degrees postnatally. The additional 8 affected family members had not sought medical care, but some were found to have signs of virilization on physical examination, while others were normal. Thus both late-onset (symptomatic) and cryptic asymptomatic) 21-hydroxylase deficiency occurred in the same pedigree. The hormonal and genetic linkage studies indicate that the late-onset (symptomatic) form of 21-hydroxylase deficiency, like the cryptic (asymptomatic) and classical forms of 21-hydroxylase deficiency, is transmitted by an autosomal recessive gene which is linked to HLA-B. Furthermore, the classical form of 21-hydroxylase deficiency associated with prenatal virilization is transmitted by an allelic variant for steroid 21-hydroxylase different from that of the nonclassical forms, late-onset (symptomatic) and cryptic (asymptomatic) 21-hydroxylase deficiency. Although these latter 2 disorders have different clinical manifestations, they demonstrate a similar degree of steroid 21-hydroxylase deficiency that is less severe than that observed in classical 21-hydroxylase deficiency. The hormonal and genetic linkage data indicate that cryptic (asymptomatic) and late-onset (symptomatic) 21-hydroxylase deficiency result from the same allelic variant at the steroid 21-hydroxylase locus. A glossary of terms is presented to describe the various allelic forms of 21-hydroxylase deficiency with consistency.

Adolescent↗
PubMed1981

Genetic and hormonal characterization of cryptic 21-hydroxylase deficiency.

Cryptic 21-hydroxylase deficiency has been previously described in asymptomatic family members of patients with classical congenital adrenal hyperplasia (CAH). These family members were detected by high baseline 17-hydroxyprogesterone levels found in the course of family studies. The hormonal responses to ACTH of the family members with cryptic 21-hydroxylase deficiency were determined and compared to the responses of patients with CAH, patients with acquired adrenal hyperplasia, family members predicted to be heterozygous for CAH, family members predicted to be unaffected, and the general population. The ACTH-stimulated levels of 17-hydroxyprogesterone and delta 4-androstenedione in the cryptic family members were elevated above the level of the general population or family members heterozygous for classical CAH, but below that of patients with CAH. The hormonal profile of patients with cryptic 21-hydroxylase deficiency is similar to that of patients with acquired adrenal hyperplasia. The response of family members heterozygous for the cryptic gene (21-OH CRYPTIC/21-OH NORMAL) was indistinguishable from that of family members heterozygous for the classical CAH gene (21-OH CAH/21-OH NORMAL). These studies support our previous proposal that patients with cryptic 21-hydroxylase deficiency are genetic compounds, having one gene for a severe enzyme deficiency and one gene for a mild 21-hydroxylase deficiency. Thus, the 21-hydroxylase genotype in cryptic 21-hydroxylase deficiency is 21-OH CAH/21-OH CRYPTIC.

Adolescent↗
PubMed1981

HLA linkage and B14, DR1, BfS haplotype association with the genes for late onset and cryptic 21-hydroxylase deficiency.

Classical congenital adrenal hyperplasia due to 21-hydroxylase deficiency (21-OH-def) has been established to be an HLA-linked, recessive monogenetic disease. However, two nonclassical forms of 21-OH-def have also been described: "cryptic" 21-OH-def, which has been shown to be HLA-linked, and "late onset" 21-OH-def, for which the status of linkage to HLA has been less certain. We now describe studies of eight additional unrelated probands with symptomatic, "late onset" 21-OH-def, and conclude that this form is also HLA-linked. Both "late onset" and "cryptic" 21-OH-def are highly associated with the same HLA antigens and markers (HLA-B14, HLA-DR1, and Bf type S) in individuals from different ethnic and geographical backgrounds. Since both "late onset" and "cryptic" 21-OH-def appear to occur in individuals with one classical 21-OH-def (21-OHCAH) allele who in addition have another 21-OH-def allele, as well as in individuals who appear to be homozygous for variant 21-PH-def alleles, and since both late onset and cryptic 21-OH-def appear to occur in the same families, our data suggest that these syndromes may represent different clinical expressions of similar or identical nonclassical 21-OH-def alleles.

Adolescent↗
PubMed1980

Cryptic 21-hydroxylase deficiency in families of patients with classical congenital adrenal hyperplasia.

Serum androgens and 17-hydroxyprogesterone concentrations and HLA genotypes were determined in 124 families of patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency (CAH). In 8 pedigrees, we discovered 16 pubertal or postpubertal family members of either sex who had biochemical evidence of 21-hydroxylase deficiency but were without clinical symptoms of excess virilism, amenorrhea, or infertility. We designated these family members as individuals with cryptic 21-hydroxylase deficiency. Within each generation, the family members with cryptic 21-hydroxylase deficiency were HLA identical. It is proposed that these family members are genetic compounds, having 21-hydroxylase deficiency as a result of two recessive gene defects: 1) a severe 21-hydroxylase gene defect present in the index case with classical CAH (21-OHCAH) and 2) a mild 21-hydroxylase gene defect (21-OHCRYPTIC). Thus, the CAH genotype in the family members with cryptic 21-hydroxylase deficiency is 21-OHCAH/21-OHCRYPTIC. Lod score analysis for linkage between the cryptogenic 21-OH trait and HLA gave a combined Lod score for males and females of theta = 0.00 of 3.409. Close genetic linkage between HLA and 21-OHCRYPTIC was thus established. This study provides support for the previously reported heterogeneity of 21-hydroxylase deficiency which may result from allelic variability at the locus for steroid 21-hydroxylase.

17-alpha-Hydroxypregnenolone↗
PubMed1976

Hysterical polydipsia (compulsive water drinking) in children.

Two patients had entirely different clinical presentations of hysterical polydipsia: convulsions and coma in a 5-year-old boy with intrinsic renal disease and a single kidney, and abnormal behavior in a 3-year-old girl with normal kidneys. In neither case was the correct diagnosis made on initial evaluation. Physiological studies demonstrated primary polydipsia to be responsible for both clinical presentations. The differential diagnosis of polydipsia and polyuria is reviewed, and the nonuniform presentation of hysterical polydipsia is emphasized. In children with intrinsic renal disease, hysterical polydipsia may be life-threatening.

Child, Preschool↗