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Biomedical subjects

G Kuhn

Publications and source records attributed to G Kuhn.

At least 19 recordsLinked to original sources
PubMed1993

Coexpression of PMP22 gene with MBP and P0 during de novo myelination and nerve repair.

The recently cloned PMP22 gene, the rat variant of the murine growth arrest-specific gene gas3, encodes a new 22 kD integral membrane glycoprotein of peripheral myelin. By means of in situ hybridization and immunohistochemistry, we have (1) analyzed PMP22 expression in myelinated and nonmyelinated peripheral nerves, and (2) compared the spatio-temporal changes in the expression of PMP22 mRNA with the expression of the myelin genes P0 and MBP (myelin basic protein) in developing as well as degenerating and regenerating sciatic nerve of rat. (3) We further investigated the expression of PMP22 mRNA by Northern blot in cultured Schwann cells maintained under different conditions of cell growth and arrest. Expression of PMP22 mRNA is restricted to Schwann cells of myelinated peripheral nerve. Transection of sciatic nerve in adult rat leads to a simultaneous and rapid decline in both PMP22 and P0 mRNA to nondetectable levels in the degenerating distal stump. When a demyelinated and axon-free distal stump, as indicated by the lack of MBP and neurofilament immunoreactivity, was reanastomosed to its proximal counterpart, the coordinated reexpression of PMP22 and MBP succeeded axonal regeneration through the distal segment with a delay of 1-2 weeks. As in regenerating nerve, a striking synchrony of expression of PMP22 and P0 transcripts, as well as MBP immunoreactivity, could be observed during sciatic nerve development. Further, in vitro evidence suggests that, unlike NIH3T3-fibroblasts, expression of PMP22/gas3 is not strictly growth arrest-specific in Schwann cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Comparison of MRI and discography in the diagnosis of lumbar degenerative disc disease.

Recent reports have attempted to compare the relative value of discography and MRI in the evaluation of lumbar degenerative disc disease. None has compared the accuracy of the two techniques in regard to the detection of disc herniation specifically, and none has offered surgical correlation. In this prospective study, both techniques were used to evaluate 264 disc levels in 90 patients with incapacitating low back pain or radicular pain. The results showed an 86% agreement level both between tests and between the orthopaedist and radiologist on each test. Surgical findings agreed with diagnostic studies at 63 of 76 levels in 57 patients who underwent operative treatment. An analysis of the relative sensitivity and specificity of each test in the diagnosis of degeneration and herniation revealed that the greater sensitivity of MRI in the detection of herniation was the only statistically significant difference (p < 0.05).

Adult↗
PubMed1992

Follow-up study among model and pattern makers in an automobile company in the Federal Republic of Germany.

The follow-up of a cohort of 528 model makers and a control group of 2273 tool makers shows an unusual pattern of mortality in the model makers' cohort. In contrast to the usual ranking, malignant neoplasms are the most frequent group of cause of death followed by diseases of the cardiovascular system. The rate ratio (RR) for malignant tumors is significantly increased among model makers compared with tool makers RR = 1.8, (95% confidence level [CL] = 1.3-2.7). The sites affected by excess cancer were stomach, the genitourinary organs, and the brain. In contrast to other studies, no tumors of the large intestine have been observed. Furthermore, there is a remarkable underrepresentation of tumors of the respiratory organs. Because these results are based on a rather small number of cases, further follow-up of the cohort is warranted to draw more profound conclusions.

Adolescent↗
PubMed1991

[Elevation of the bacteriological content of milk of clinically unaffected lactating bitches of a canine research stock].

In the years 1987-1989 a bacteriological investigation of the milk was made in 44 clinically healthy postparturient bitches. In 30 animals bacteria most commonly isolated were staphylococci. 30.3% (40 samples) of the samples yielded pure cultures and 6.8% (9 samples) anacultures. Small numbers of bacteria were isolated in most of the samples; 67.4% showed moderate bacterial growth (less than or equal to 10(4)/ml sample). In vitro drug sensitivity tests revealed lincomycin, erythromycin and polymyxin B proved to be most efficient. Moreover neomycin, kanamycin and chloramphenicol showed low resistance rates while colistin sulfate and carbenicillin were less effective. A direct influence of lactiferous gland colonization with bacteria on mortality of puppies was not observed. With respect to clinical aspects, the application of antibiotics for sanitation of the lactiferous gland colonization with bacteria in clinically healthy bitches has to be considered carefully. However, for this the estimation of drug sensitivity tests is not satisfactory and should be completed by accurate bacteriological identification.

Animals↗
PubMed1991

Axon-regulated expression of a Schwann cell transcript that is homologous to a 'growth arrest-specific' gene.

We have isolated a 1.8 kb cDNA (pCD25) clone that encodes a transcript that is differentially expressed during nerve regeneration. Nucleotide sequence comparison indicates 89.6% homology with the recently identified murine 'growth arrest-specific' gene gas3. The open reading frame of the CD25 transcript predicts a 17 kDa protein with four putative transmembrane regions. Steady-state levels of the CD25 mRNA are very much higher in sciatic nerve than in other tissues, and expression in sciatic nerve is confined to Schwann cells. Following nerve injury, the transcript levels rapidly declined in nerve segments distal to the site of lesion, but recovered upon nerve regeneration. In contrast, in distal stumps of permanently transected nerves, the mRNA level remained very low. Substantial amounts of the mRNA could be reinduced only upon anastomosis of these interrupted nerve stumps. Re-induction of the mRNA followed the elongation of regenerating axons through the distal nerve segment. Our data indicate that axons regulate expression of the CD25 mRNA in Schwann cells, and suggest that the CD25 protein functions during Schwann cell growth and differentiation.

Amino Acid Sequence↗
PubMed1991

Long-term effects of ovariectomy on pituitary-adrenal axis and specific antibody response in rats.

The effects of ovariectomy on morphologically demonstrable characteristics of lymphoid tissue, pituitary, and adrenal glands as well as on plasma ACTH and corticosterone levels and humoral immunity of female Lewis rats were investigated. The present study establishes ovaries as potential regulatory organs upon thymus, pituitary, and adrenal glands in female Lewis rats. In addition to the effects on these important lymphoid organs and endocrine glands, ovariectomy influenced the time course of serum IgM antibody titres against fluorescein isothiocyanate (FITC), but had only moderate effects upon serum IgG antibody titres. In conclusion, the present results suggest that ovariectomy modifies morphological characteristics of the thymus and pituitary-adrenal axis. Furthermore, circulating corticosterone seems to play an important role in regulating antibody formation in intact compared to ovariectomized female Lewis rats, while the influence of thymic mass is far from clear.

Animals↗
PubMed1991

Long-term effects of hysterectomy and bilateral oophorectomy on lymphoid tissue in female Lewis rats.

The effects of ovariectomy, ovariohysterectomy and hysterectomy on morphologically demonstrable characteristics of lymphoid organs, peripheral white blood cell counts and antibody production against sheep red blood cells (SRBC) were studied in female Lewis rats. Removal of ovaries induced enlarged thymus weight and cellularity. No differences were observed between the groups in spleen weight, while hysterectomy together with ovariectomy influenced relative uterus draining lymph node (UDLN) weight. The percent numbers of pan T, helper T lymphocytes, cytotoxic/suppressor T cells and IgG bearing cells (B lymphocytes) of all investigated organs showed only moderate changes caused by the surgical procedures. In contrast, removal of ovaries generated elevated total leukocyte and lymphocyte counts in peripheral blood. The changes in absolute blood lymphocyte counts were accompanied by similar variations in absolute T and B lymphocyte numbers. Ovariohysterectomy had slightly greater effects on these parameters than ovariectomy alone. In addition, ovaries and uterus had only moderate influences on systemic immune responses toward SRBC. In conclusion, the present results indicate that the removal of ovaries and uterus can modify morphological characteristics of lymphoid organs and peripheral blood but antibody production showed only moderate changes caused by the surgical procedures.

Animals↗
PubMed1991

Quantitative studies of haematological values in long-term ovariectomized, ovariohysterectomized and hysterectomized rats.

The effects of ovariectomy, ovariohysterectomy and hysterectomy on total and differential white blood cell counts, distribution of T and B lymphocytes and T/B cell relationship were studied. Changes in these parameters associated with the surgical operations were observed in total leukocytes and lymphocytes, absolute and relative band neutrophils and T/B cell relationship. Results suggest that the ovaries together with the uterus are potential regulatory organs upon the absolute number of circulating leukocytes and lymphocytes in female Lewis rats. In addition to their effects upon this important population of cells, the ovaries and uterus have moderate effects upon relative T and B lymphocyte numbers in peripheral blood. In general the changes depend mainly on the removal of the ovaries and to a lesser degree on hysterectomy.

Animals↗
PubMed1991

The effect of transportation stress on circulating corticosteroids, enzyme activities and hematological values in laboratory dogs.

Stress during transportation was monitored in truck-transported Beagle dogs "IVTK HD". Cortisol (F), corticosterone (B), red and white blood cell parameters, and enzyme activities in plasma were estimated. Plasma levels of cortisol and corticosterone were increased significantly during transportation and returned to basal values overnight post arrival. Hematocrit, hemoglobin, erythrocytes and leukocytes increased moderately. No obvious differences in enzyme activities were observed. Only alpha-HBDH values dropped significantly at the end of the 9.5 h transport period. This study confirms, although individual reaction is remarkably different, transportation as a potent stressor for Beagle dogs.

11-Hydroxycorticosteroids↗
PubMed1990

Regeneration-associated high level expression of apolipoprotein D mRNA in endoneurial fibroblasts of peripheral nerve.

A cDNA clone containing the entire coding region of rat apolipoprotein D (Apo D) was isolated from a cDNA library of regenerating sciatic nerve by differential hybridization. Only small amounts of Apo D mRNA were detected in noninjured mature nerve. Moderately increased levels of Apo D transcripts were found in transected nerves, which were prevented from regeneration by ligation. In contrast, in regenerating crushed nerve, the steady-state level of Apo D mRNA transiently increased at least 40-fold above control levels at the time when axons from the proximal stump grow into the distal nerve segment. Using transverse sections and primary cell cultures from regenerating nerve, Apo D transcripts could be localized by in situ hybridization in endoneurial fibroblasts but not in Schwann cells, macrophages or perineurial and epineurial cells. Apo D protein (Mr 32.8 kd) was secreted and accumulated in the endoneurial extracellular space where it could be detected in lipoprotein fractions by immunoblotting using established antibodies to human Apo D. High level expression of Apo D mRNA seems to be a novel regeneration-associated molecular event of endoneurial fibroblasts indicating a function for Apo D and fibroblasts in nerve repair.

Amino Acid Sequence↗
PubMed1990

Methemoglobinemia as a cause of coma.

A 50-year-old man presented to the emergency department in a coma with fixed and dilated pupils. Skin and mucous membranes were noted to be an ashen grey color. Initial vital signs were blood pressure of 104/70 mm Hg; pulse, 110; and respirations, 12. Initial arterial blood gases were pH of 7.25; PaCO2, 26.6 mm Hg; PaO2, 22.1 mm Hg; oxygen saturation, 15.2%; and methemoglobin level, 81.5%. Venous and arterial blood samples were chocolate brown, and it was noted that the color did not change when 100% oxygen was bubbled through the blood. Methylene blue 140 mg was given intravenously, and the patient gradually became more responsive. He was discharged three days later with no neurologic deficits. A comprehensive literature search revealed no reported cases of complete patient recovery with this high a methemoglobin level.

Coma↗
PubMed1990

[Fat clogging, fat cell count and fat cell size in swine in relation to age and feeding intensity].

Growth dependent changes of fat gain, the number of fat cells in the cutlet muscle and the size of the fat cells in the bacon of the back were studied in dependence on feeding intensity with a total of 145 male castrates of the genotype (L X E) XSF. Between their 5th and 32nd weeks of life the animals were butchered at intervals of 3 weeks and the parameters were determined. The gain of fat and the intramuscular fat content were highest in the high-level variant (daily weight gain 720 g) and lowest in the low-level variant (daily weight gain 530 g). The diameter of the fat cells in the middle layer of the bacon of the back increased up to an age of 26 weeks and then remained constant. Differences between the feeding groups were registered; the animals of the high-level group had the biggest fat cells from the 14th week onwards. A nutrition-caused difference between the number of fat cells per mm2 of the cutlet muscle could not be found. The calculated total number of fat cells in the cutlet muscle increased due to growth up to an age of 26 weeks. The results provided basic knowledge of fat gain and influences on it in pigs and they indicate possibilities of making statements on fat retention determining the microstructure of the fat tissue of the living animal by means of biopsy.

Adipose Tissue↗
PubMed1989

Self-administration of small amounts of morphine through glass micropipettes into the ventral tegmental area of the rat.

A micropipette-system was used to investigate intracranial self-injection of morphine in the rat. The system consisted of a glass micropipette (tip dia 5 microns) connected by flexible tubing and a swivel to a pressure source. Using nose-poking through a hole in one wall of the cage as the operant, rats self-injected quantities as small as 50 ng/5 nl of morphine into the ventral tegmental area. In contrast, rats in the saline-treated group and yoked-control group did not increase their rates of nose-poking behaviour above baseline levels. Intermittent reinforcement in the morphine-treated group resulted in a further increase in the rate of nose-poking. Histological inspection of the site of injection revealed minimal damage to brain tissue and likely confinement of the injected solution to the area around the tip of the pipette.

Animals↗
PubMed1989

[Neoplastic invasion of the pulmonary arteries. Evaluation by MRI. Preliminary experience].

Bronchial tumors invading the mediastinum are no longer systematically regarded as inoperable. Curative surgery has produced a significant survival rate and led to the adaptation of the TNM classification. The degree of invasion of the pulmonary artery is a criterion of operability. The authors are trying to assess the role of MRI with regard to CT and DSA for the measurement of invasion. Their study deals with the prospective assessment of ten patients. The MRI examinations have been carried out with a 0.5 and 1.5 T supraconductive magnet (Philips Gyroscan). Cardiac gating has been used for acquisition. The planes of section are axial, transverse or oblique along the greater axis of the pulmonary arteries. CT examinations in 9-mm thick sections with and IV contrast injection demonstrate the contact of the tumor with the mediastinum. The digital angiograms have been taken with an intravenous injection into a vein of the bend of the elbow or into a femoral vein. Six cases have been verified at surgery. In all cases, the invasion predicted with MRI proved to be correctly assessed. In three cases, MRI provides additional information to the combined findings of CT and DSA. MRI is a good complement for the preoperative assessment of patients with large tumors invading the mediastinum but for which curative surgery is indicated.

Bronchial Neoplasms↗
PubMed1987

Solitary myeloma.

Explore the source record for details and available documents.

Angiography↗