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Biomedical subjects

M Corbett

Publications and source records attributed to M Corbett.

At least 19 recordsLinked to original sources

Purification of a pituitary receptor for somatostatin. The utility of biotinylated somatostatin analogs.

A somatostatin (SRIF) receptor and its associated Gi regulatory proteins was purified from GH4C1 rat pituitary cells by: 1) saturation of the membrane-bound receptor with biotinyl-NH-[Leu8,D-Trp22,Tyr25] SRIF28 (bio-S28); 2) solubilization of receptor-ligand (R.L) complex with deoxycholate-lysophosphatidylcholine (D.L); 3) adsorption of solubilized receptor-ligand complex to immobilized streptavidin; and 4) elution of receptor and G-protein by GTP. The receptor, a glycoprotein with an average M(r) of 85,000, was then purified to substantial homogeneity on immobilized wheat germ agglutinin. The 85-kDa glycoprotein was identified as a SRIF receptor by several criteria. (a) It had the same size as the chemically cross-linked R.[125I]L complex. (b) Yield of the purified protein increased and plateaued in the same range of bio-S28 concentrations where specific high affinity binding reached saturation. (c) It was copurified with appropriate G-protein subunits. The 85-kDa receptor and two other proteins with M(r) values of 35,000 and 40,000, the sizes of G beta and G alpha, did not appear in eluates from control streptavidin columns done with SRIF receptors loaded with nonbiotinylated S14. The 40-kDa protein was identified as a Gi alpha by ADP-ribosylation from [32P]NAD catalyzed by pertussis toxin. (d) Both the chemically cross-linked R.[125I]L complex and SRIF receptor purified from [35S]methionine-labeled GH4C1 cells were reduced in size to about 38 kDa by endoglycosidase F. (e) Amino acid sequence from the purified receptor was nearly identical with that of a recently cloned SRIF receptor subtype.

Adenosine Diphosphate Ribose

Partial amino acid sequence of a somatostatin receptor isolated from GH4C1 pituitary cells.

A somatostatin receptor isolated from GH4C1 rat pituitary tumor-derived cells was cleaved with cyanogen bromide or cyanogen bromide+trypsin to obtain sequenceable fragments. Five unique amino acid sequences ranging from 6 to 27 amino acid residues were obtained. The sequence was identical to sequence recently reported for one of two somatostatin receptors cloned from human pancreas [Yamada et al., (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 251-255] except for a single valine to isoleucine substitution. This is the first report of amino acid sequence from a purified somatostatin receptor.

Amino Acid Sequence

Magnetic resonance imaging evaluation of calcaneal fat pads in patients with os calcis fractures.

Destruction of the calcaneal fat pad has been implicated as a source of chronic pain following fractures of the os calcis. Several investigators postulate that the initial trauma that produces a calcaneal fracture also results in destruction of the U-shaped fibrous septa that maintain the piston-like organization of the fat columns. Fibrosis and loss of the protective cushioning provided by the fat pad may eventually occur. The authors report on the largest series of magnetic resonance images of the calcaneal fat pad in the heels of patients with calcaneal fractures. A prospective consecutive study utilizing magnetic resonance imaging was performed on 22 heels with calcaneal fractures. Ten contralateral heels without calcaneal fracture and the heels of five normal subjects were scanned as controls. No signal changes suggestive of increased fat pad edema, fibrosis, or fatty release were detected. In addition, the vertical septa were well visualized and found to be intact in all cases. The height of the fat pad was measured, with no changes noted as compared with the contralateral heel. In those patients with acute fractures, signal changes suggestive of hematoma were well visualized in the soft tissue surrounding the calcaneus. In two of these cases, there was extension beneath the plantar fascia, but no penetration into the fat columns. Magnetic resonance imaging allows excellent detailed visualization of the calcaneal fat pad and surrounding structures. No evidence is found to support the hypothesis that marked damage to the gross structure of the fat pad occurs at the time of injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue

Impact of short-term oral steroid use upon children's school achievement and behavior.

Physicians need clarification of whether the temporary use of adrenal corticosteroids to abort acute asthma can adversely effect school achievement and behavior problems. Nineteen nonsteroid-dependent asthmatic children were given prednisone orally while all other medications were kept constant. Five days later, when they were seen in the physician's office, an academic achievement test was administered to the child; and the child, a parent, and a teacher completed behavior rating surveys. After 2 weeks off the steroids the child returned to the physician's office and the achievement test and rating scales were completed again. There was no significant difference between the achievement test scores and behavior ratings in school or at home under the two conditions. Short-term use of oral steroids does not impair children's basic academic skills nor their behavior at school or home.

Administration, Oral

Case report 85.

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Adult

The production of prostaglandins in response to experimentally induced osteomyelitis in rabbits.

Osteomyelitis was induced in the tibiae of rabbits by injection of staphylococcus aureus and sodium tetradecylsulphate (STD); additional rabbits were injected with STD alone. Confirmation of osteomyelitis was based on positive culture of the same phage type bacteria from the tibiae and on the characteristic radiographical and histological appearance of osteomyelitis. Only tibiae which proved to be infected by the above criteria showed significantly increased in vitro release and content of Prostaglandin E and Prostaglandin F2 alpha compared with tibiae injected with STD (P less than 0.05). After two weeks infection, infected tibiae released nine times more Prostaglandin E and five times more Prostaglandin F2 alpha than tibiae injected with STD alone. After four weeks infection, infected tibiae released less Prostaglandin E (P less than 0.05) than after two weeks infection but the release of Prostaglandin F2 alpha was similar. The production of large amounts of prostaglandins by bones in response to infection may be the cause of the rapid bone resorption and sequester formation observed in osteomyelitis.

Animals

Changes in load bearing in the rheumatoid foot.

A study of peak force exerted under areas of the foot was made in 27 patients with rheumatoid disease and in 30 normal persons. Patients were found to exert considerably less force under their toes and under the first metatarsal head and more force under the 3 outer metatarsal heads. It was possible to correlate these changes with increasing clinical and radiological severity.

Adult

Radiographic changes in early rheumatoid disease.

We have studied the radiological features in 94 patients with early rheumatoid disease followed prospectively for 5 years. The changes appeared very early and occurred in up to 71-3% of patients. Erosive changes occurred in the feet much more commonly than in the hands and considerably earlier. Erosive changes were present before there was joint-space loss. Frequent x-ray examination of feet and hands in the first 2 years after presentation is required if we are to identify patients at risk for serious joint damage.

Arthritis, Rheumatoid

Pain in the knee associated with osteoporosis of the patella.

Four patients, all of whom complained of pain in the knee, were found to have radiological evidence of osteoporosis particularly marked in the patella. In 3 a neurological lesion at the appropriate spinal segment was present, and the fourth patient, who was frankly hysterical, had an autonomic disturbance. If radiological porosis is isolated to the patella a distant cause such as nerve irritation should be sought.

Adult

Relationship of radiological change to clinical outcome in rheumatoid arthritis.

Ninety-four patients with rheumatoid arthritis, seen within the first year after onset, have been followed prospectively with annual radiographs for a mean 63-1 months. An erosive arthropathy occurred in 72. The severity of the erosive changes showed a significant correlation with eventual clinical outcome. It is possible to predict a favourable outcome in those patients whose erosive changes become static at an early stage in the disease.

Arthritis, Rheumatoid

Extra-articular features in early rheumatoid disease.

One hundred and two patients who presented with rheumatoid disease within the first year of onset were studied prospectively every four months for a mean 4.5 years to assess the incidence of extra-articular features. The features that seemed to be common in the early stages included hand-muscle wasting, carpal tunnel syndrome, lymphadenopathy, non-specific ankle swelling, and rheumatoid nodules, and to a lesser extent hepatomegaly, being underweight, conjunctivitis, skin transparency, and a palpable thyroid gland. Those features which seldom occurred early included scleromalacia, temporal artery inolvement, salivary gland enlargement, distal-motor neuropathy, splenomegaly, digital vasculitis, and pulmonary and cardiac complications. Being underweight indicated a significantly more severe outcome.

Adult