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Biomedical subjects

P C Johnson

Publications and source records attributed to P C Johnson.

At least 19 recordsLinked to original sources
PubMed1979

Paraneoplastic vasculitis of nerve: a remote effect of cancer.

The development of mononeuritis multiplex brought three men to medical attention weeks to months prior to the diagnosis of a malignancy. In each case, sural nerve biopsy exhibited active wallerian degeneration with vasculitis. Two of the men died and at autopsy were found to have clinically unrecognized oat cell carcinoma and carcinomatous sensory neuropathy with brainstem encephalitis. The third patient is still alive but was found to have a lymphoma and has subsequently developed a liposarcoma. The vasculitis in all 3 cases seems limited mainly to the peripheral nervous system. Mononeuritis multiplex due to vasculitis may represent a new remote effect of cancer on the nervous system.

Brain Stem↗
PubMed1979

Brain neurotransmitter receptors in Friedreich's ataxia.

The binding of 3H-quinuclidinyl benzilate, a muscarinic cholinergic antagonist, of 3H-dihydroalprenolol, a beta adrenergic antagonist, and of 3H-flunitrazepam, a ligand which labels benzodiazepine receptors, was examined in several regions of control and Friedreich's ataxia (FA) brains. 3H-Quinuclidinyl benzilate binding appeared to increase in the inferior olivory nucleus, anterior and posterior cerebellar vermi but was unaltered in the dentate nucleus and cerebellar hemisphere of FA brain. The binding of 3H-dihydroalprenolol seemed to increase in the inferior olivary nucleus yet was not different from controls in the dentate nucleus, cerebellar hemisphere, anterior and posterior cerebellar vermi of FA brains. 3H-Flunitrazepam binding was slightly lowered in the inferior olivary and dentate nuclei but was unchanged in the other FA brain regions examined. The present study suggests possible trends in neurotransmitter receptor alterations in post-mortem brain tissue of FA patients.

Adult↗
PubMed1979

Selective polymyositis inducted by coxsackievirus B1 in mice.

A high-passage laboratory strain of coxsackievirus B1 produced a unique myositis that predominantly and profoundly affected hip extensors and, to a lesser extent, hindquarter knee flexors when inoculated into a strain of random-bred newborn mice of Swiss origin (COH mice). The effect was not observed in BALB/c or C3H mice similarly inoculated. In addition to the differences in susceptibility of the mouse strains, it was found that six different low-passage "field" isolates of coxsackie-virus B1 isolated from infected patients varied considerably in their capability to induce these lesions. Thus, selective myositis which is muscle group-specific can be induced in a mouse model with coxsackievirus B1, and both genetic factors of the host and characteristics of the virus strain play a significant role in the pathogenesis of the myositis.

Animals↗
PubMed1978

Intestinal muscle and mucosal blood flow during direct sympathetic stimulation.

The effect of direct sympathetic stimulation on intestinal muscle and submucosal-mucosal vasculatures was studied in the anesthetized rat. Blood flow was calculated from direct measurements of vessel diameter and red cell velocity. Stimulation at 4 Hz caused a slight reduction (4%) in muscle flow, but had no measurable effect on submucosal-mucosal flow; stimulation at 8 and 16 Hz caused muscle flow to decrease to 58.3 +/- 8.7% (SE) and 31 +/- 5.1%, respectively, of control flow, and mucosal flow, to 73 +/- 3.4% and 54.1 +/- 1.2%, respectively, of control flow. Calculations of muscle and mucosal vascular resistances from flows and microvascular pressures indicate that muscle resistance increased proportionately more than mucosal resistance at 4 and 8 Hz. However, during stimulation at 16 Hz, the mucosal resistance is only 55% of control, and muscle resistance is not significantly (P less than 0.05) different from control. Therefore, reduction of muscle and mucosal flows during 16-Hz stimulation must be caused by the intestinal arterioles and venules in series with these vasculatures.

Animals↗
PubMed1978

Evaporative water loss in man in a gravity-free environment.

Daily evaporative water losses (EWL) during the three Skylab missions were measured indirectly using mass and water-balance techniques. The mean daily values of EWL for the nine crew members who averaged 1 h of daily exercise were: preflight 1,750 +/- 37 (SE) ml or 970 +/- 20 ml/m2 and inflight 1,560 +/- 26 ml or 860 +/- 14 ml/m2. Although it was expected the EWL would increase in the hypobaric environment of Skylab (one-third atmosphere). an average decrease from preflight sealevel conditions of 11% was measured. The results suggest that weightlessness decreased sweat losses during exercise and possibly reduced insensible skin losses as well. The weightlessness environment apparently promotes the formation of an observed sweat film on the skin surface during exercise by reducing convective flow and sweat drippage, resulting in high levels of skin wettedness that favor sweat suppression.

Body Water↗
PubMed1978

Low-temperature urine collection apparatus for laboratory rodents.

An apparatus for the collection of urine at -19 degrees C from unrestrained small laboratory animals was developed. The cooling unit accommodated five rodent metabolism cages for the collection of urine volumes up to 50 ml per collection period. The unit operated continuously for 5--6 weeks with no maintenance other than removal of the urine specimens, cleaning of the cages and collection dishes, and provision of feed and water.

Animals↗
PubMed1977

Hematogenous metastases of carcinoma to dorsal root ganglia.

Hematogenous metastases of carcinoma to dorsal root ganglia was found in 2 of approximately 500 consecutive autopsies in which a lumbar dorsal root ganglion was routinely examined microscopically. The primary tumors were poorly differentiated colonic adenocarcinoma and oat cell carcinoma of the lung, both with widespread hematogenous metastases which spared the central nervous system. No symptoms were detected clinically. In the same series of patients the sural nerve as well as the lumbar plexus were histologically sampled but no examples of distant endoneurial metastases were found. The vascular endothelium of dorsal root ganglia is fenestrated and, presumably as a consequence, provides no blood-ganglion barrier. This microvascular difference may account for the susceptibility of the ganglia to metastases when compared to nerve trunks which posses unfenestrated endothelium and blood-nerve barrier.

Adenocarcinoma↗