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Biomedical subjects

J Christensen

Publications and source records attributed to J Christensen.

334 records · Page 19Linked to original sources
PubMedDate not supplied

Structure of mink immunoglobulin gamma chain cDNA.

Two cDNA clones, encoding mink Ig gamma chains were characterized. The pIGG47 clone contains a part of the leader segment, VDJ and C regions, and pIGG14 contains a part of the J and a complete C region. The clones differ by only four nucleotides in the C region, and they most probably represent allelic variants of the same gene. The V gene segment of pIGG47 was found to be highly similar to human VHIII subgroup sequences; there was 86-87% similarity for the whole V gene segment and 91% for the VHIII specific regions (codons 65-87). Southern blot analysis demonstrated that a high proportion of mink VH genes is VHIII related. The V gene segment used as a probe revealed 19-23 bands in mink DNA under stringent conditions. This is in agreement with our previous data showing that a high proportion of mink Ig contains an 'alternative' binding site for protein A, a feature common to VHIII-related molecules. According to Southern blot analysis there may be 5-7 C gamma genes at the mink IgH locus.

Amino Acid Sequence↗
PubMedDate not supplied

Intramucosal nerve cells in human small intestine.

We investigated the intramucosal nerve cells of the human small intestine with histochemical methods to demonstrate nicotinamide adenine dinucleotide diaphorase and acetylcholinesterase and with morphometry. Intramucosal neurons appeared as solitary cells or in small groups, especially in the ileum. Most intramucosal nerve cell bodies were round or oval; some were flat or spindle-shaped. They mostly lay close to the muscularis mucosae, but some were located within the muscularis mucosae and others were some distance away from it. The processes of some mucosal neurons projected towards the submucosa. Most mucosal nerve cells showed acetylcholinesterase activity. The frequency distribution of nerve cell profile areas in the intramucosal cells in the duodenum differed from that of cells in the ileum (P < 0.001). There were more large mucosal nerve cells in the mucosa of the duodenum than in the ileum. There was no significant difference between the frequency distributions of cell profile areas of cells of the mucosa and cells of Meissner's and Henle's plexuses in the same region. We conclude that intramucosal nerve cells, similar to those of the submucosal plexus, exist in the human small intestine. The size of intramucosal nerve cell profiles differs between the duodenum and ileum. This is consistent with their possible different functions.

Acetylcholinesterase↗
PubMedDate not supplied

Distribution of NADPH diaphorase in intramural plexuses of cat and opossum esophagus.

Nonadrenergic noncholinergic (NANC) nerves, releasing nitric oxide (NO), regulate peristalsis in esophageal smooth muscle. The NADPH diaphorase reaction identifies nitric oxide synthase (NOS). NO-synthesizing (NANC) nerves should be more abundant in esophageal smooth muscle than in striated muscle. We used NADPH diaphorase histochemistry in whole-mounts of the esophagus of cat (predominantly striated muscle) and opossum (predominantly smooth muscle) to compare striated and smooth muscle regions. In the opossum myenteric plexus, 90% of nerve cells were stained, with two populations, dark-staining and light-staining cells. Dark cells constituted 35-51% of stained cells with no difference between striated muscle and smooth muscle regions. In the cat myenteric plexus, 50% of cells were unstained in the striated muscle segment, but only 10% in the smooth muscle segment. Stained cells constituted two populations, dark cells and light cells, dark cells making up 48-60% of stained cells in both striated and smooth muscle segments, with no difference between segments. Both dark cells and light cells lay in clusters in opossum, but not in cat. Dark cells showed no selectivity for large or small ganglia of myenteric plexus in either region in opossum. Many more NADPH diaphorase positive nerve fibers lay in the circular smooth muscle layer than in the other layers. They were not found in striated muscle. Interstitial cells of Cajal in the circular layer of smooth muscle were also positive. In the submucosal plexus of opossum, all cells were stained, 10% being dark cells in both striated and smooth muscle segments. The cat has almost no nerve cells in the submucosal plexus. The similarity of the myenteric plexus in striated muscle and smooth muscle regions of the esophagus suggests that NADPH diaphorase positive nerves have other functions besides regulation of smooth muscle. Also, a positive reaction may not dictate that NO is the sole transmitter released.

Animals↗
PubMedDate not supplied

Monitoring CBF in clinical routine by dynamic single photon emission tomography (SPECT) of inhaled xenon-133.

A very simple and low-cost brain dedicated, rapidly rotating Single Photon Emission Tomograph SPECT is described. Its use in following patients with ischemic stroke is illustrated by two middle cerebral artery occlusion cases, one with persistent occlusion and low CBF in MCA territory, and one with early lysis of the occlusion having high CBF (massive luxury perfusion) for some weeks. Evidence of this kind may be essential in the evaluation of therapeutic measures in ischemic stroke.

Brain↗
PubMedDate not supplied

[Parathion poisoning in cattle (author's transl)].

In a herd of dairy cattle half of the cows showed symptoms of acute poisoning. Blood- and hair samples were taken from seven of the cows, of which two did not show any clinical symptoms. The cholinesterase activities were in all the blood samples decreased to about 10 per cent of normal and parathion was found in all hair samples. The cholinesterase activities rose gradually during a 31/2 month period to the lower part of the normal range. Parathion was found in samples from the inner walls of the cowstable, and it was concluded that the poisoning was probably due to parathion spraying in the stable, while a suspicion of winddrift as a source of poisoning was rejected as less probable.

Aerosols↗
PubMedDate not supplied

Local arterial versus systemic adriamycin infusion therapy for sarcoma transplanted in the rat kidney.

The course of growth of a 20-methyl-cholanthrene-induced sarcoma was studied in the rat kidney. The volume growth was exponential, with a volume doubling time of approximately 20 hours from day 6 to day 10 after implantation. The potential doubling time, as assessed by the stathmokinetic method with colcemid, was 18 hours during this period. After treatment with adriamycin (Adm) at 5 mg/kg body weight, a tumor growth delay of 3 days was seen in animals given Adm by selective, constant-rate infusion into the renal artery; in contrast to a 2 days' delay for the animals given intravenous (i.v.) Adm. The mitotic index was significantly lower in tumors given intra-arterial (i.a.) infusion of Adm compared to i.v. administration 24 hours after treatment. No significant difference in mitotic index was seen after 48 hours. From day 4 after treatment, all tumors had recovered to the same exponential volume growth as the untreated controls. At day 8 after treatment, the difference between the treatment groups had vanished and no significant difference was seen between i.v. treated tumors and untreated controls. Simultaneous i.v. infusion of Angiotensin-II (in order to increase the concentration of the selectively infused Adm) during i.a. infusion gave no further effect on tumor volume growth or mitotic index. The variation in effect with selective arterial infusion may be due to partial obstruction of the renal circulation by the catheter, as shown by renal blood flow measurements with radio-nuclide-labeled microspheres, administered before and after the selective catheterization.

Analysis of Variance↗