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Biomedical subjects

C Marks

Publications and source records attributed to C Marks.

At least 73 records · Page 4Linked to original sources
PubMed1980

The sodium effect of Bacillus subtilis growth on aspartate.

aspH mutants of Bacillus subtilis have a constitutive aspartase activity and grow well on aspartate as sole carbon source. aspH aspT mutants, which are deficient in high affinity aspartate transport as a result of the aspT mutation, grow as well as aspH mutants in medium containing high concentrations of aspartate and Na+. This Na+ effect is not due to an enhancement of aspartate transport but is the result of increased cellular metabolism. The ability to grow rapidly in sodium aspartate is induced by prior growth in the presence of Na+. In potassium aspartate, the addition of arginine, citrulline, ornithine, delta 1-pyrroline-5-carboxylase or proline instead of Na+ also allows rapid growth; but in a mutant deficient in ornithine--oxo-acid aminotransferase, only pyrroline-carboxylate or proline can replace Na+. The amino acid pool of cells growing slowly in potassium aspartate contains proline at a low concentration which increases upon addition of proline (but not Na+) to the medium. Thus, Na+ addition does not increase the synthesis of proline, but proline or pyrroline-carboxylate acts similarly to Na+ either in preventing some inhibitory effect (by aspartate or the accumulating NH4+) or in overcoming some deficiency (e.g. in further proline metabolism.

Amino Acids↗
PubMed1978

Bronchial carcinoids and hormonal disorder.

The relationship between bronchial carcinoids and hormonal disorder is reviewed in the light of a study of 24 patients with carcinoid tumors of the bronchus. In this series, two patients presented with manifestations of the polyendocrine disorder. The common origin of carcinoid tumors and other APUD cells from neural crest ectoderm provides a common denominator in the association of carcinoid tumors of the bronchus and adenomas, or carcinoma of associated endocrine organs.

Adenoma↗
PubMed1977

The cellular structure of bronchial carcinoids.

A histological and electronmicroscopic study of bronchial carcinoids indicated that these tumours are argyrophilic in keeping with their occurrence in tissue of embryologically foregut origin. Normal bronchi contain cells that resemble, in their electronmicroscopic content, intestinal Kultschitzky-type cells. Characteristic of the carcinoid cell is the presence of intracellular neurosecretory granules seen on electronmicroscopy despite the apparent absence of argentaffin granules under light microscopy.

Bronchial Neoplasms↗
PubMed1977

Bronchial adenoma. A clinicopathologic study.

Among 28 patients with bronchial adenomas, 24 adenomas (86%) were of the carcinoid type. The 28 bronchial adenomas provided an incidence of 0.6% of all primary lung tumors seen in our institutions. There was a slightly greater preponderance of female patients and a greater incidence of the lision occurring in the right bronchopulmonary tree than the left. Symptoms of bronchial adenoma may exist for many years before the condition is diagnosed, and prolonged survival is recorded, even in the absence of surgical treatment. Although pneumonectomy was performed in several patients, lobectomy, bronchoplastic procedures, or sleeve resection of the affected area are generally recommended.

Adenoma↗
PubMed1976

Aspects of treatment. The anatomical basis for portal decompressive surgery.

Definitive surgical techniques used in the treatment of portal hypertension all aim to achieve portal venous decompression. The historic development of the various procedures currently employed provides a broad repertoire of surgical operations. Each of the procedures merits consideration and may be specifically indicated in a given situation. Description of the operative steps emphasizes the importance of the anatomical relationships of the various structures.

Blood Vessel Prosthesis↗
PubMed1976

Renal transplantation: an analysis of operative complications.

Review of 112 renal transplants in 95 patients with end-stage renal disease revealed a wound infection rate of 18 percent. The incidence of infection was unquestionably greater if drains were placed in the wound. An 8.8 per cent incidence of pulmonary infection was represented by lung abscess, bronchopneumonia and necrotizing pneumonitis. Three deaths were attributable to fungal infections-candida sepsis, cryptococcal sepsis, and Nocardia brain abscess. In 14 per cent of this series vascular anastomotic complications occurred, and were attributable to stenosis, thrombosis, or hemorrhage. The complications of ureterovesical anastomosis include urinary fistulas and ureteral obstruction.

Anti-Inflammatory Agents↗
PubMed1975

An electron microscopic study of the effects of portacaval shunts on the ultrastructure of the rat liver after partial hepatectomy.

The normally quiescent stable adult liver has a generous capacity for reparative hypertrophy and hyperplasia after loss of functional tissue. The large reserve of the liver's functional capacity permits survival of the animal even if over 70 per cent of its liver is removed. It retains an inherent capacity for regenerative growth which subsides once the original organ deficit is restored. This study attempted to resolve the question of whether alteration in hepatic hemodynamics affects the regenerative stimulus of the liver after partial (70 per cent) hepatectomy. It has shown that the liver remnant regenerates after reduction of portal blood flow by construction of a portacaval anastomosis. The diversion of blood from the liver exerts its own histologic and electron microscopic effects on the liver. Reduction of portal blood flow affects the temporal patterns of regeneration after partial hepatectomy but does not prevent completion of the regenerative process. Correlation of this study with the biochemical data available in the literature indicates that the structural changes in the cellular organelles during the process of regeneration reflect dynamic biochemical events that are based on a predetermined genetic code representing the key to life that is uniquely found in the liver.

Animals↗
PubMed1975

Gallstone ileus. Review of the literature and presentation of thirty-four new cases.

An analysis of thirty-four patients with gallstone ileus is integrated with a review of the literature on the subject. Surgical treatment was carried out in thirty-two patients, with an overall operative mortality of 19 per cent. Three patients were treated by one stage enterolithotomy, fistula repair, and cholecystectomy without operative mortality, emphasizing the merit of one stage treatment in selected, well prepared patients. A 6 per cent incidence of carcinoma of the gallbladder was noted in this series of patients.

Adult↗
PubMed1974

Carcinoid tumors of the gastrointestinal tract.

The charts of 135 patients with gastrointestinal carcinoid tumors diagnosed over a 22-year period at 2 hospitals are reviewed and the clinical and pathological aspects discussed. Carcinoids occur most commonly in the appendix, jejunoileum, and rectum. Those smaller than 1 cm in diameter provide evidence of malignant potential only occasionally; lesions in the 1-1.9 cm range do this quite variably, and tumors 2 cm and larger are almost always invasive or metastatic or both. All gastrointestinal carcinoids except those of the appendix enlarge, invade, and metastasize predictably if given sufficient time. Most carcinoids except those of the rectum have already been adequately treated surgically when diagnosed by the pathologist. Local excision is effective treatment for noninvasive rectal carcinoids smaller than 2 cm in diameter, but those that have invaded or grown to 2 cm should undergo more radical resection. In general, gastrointestinal carcinoids carry better prognoses than do adenocarcinomata, and even in the presence of distant metastases long-term survival occurs in a significant number of patients. The frequent concomitance of associated malignant diseases accounts for as many or more deaths in these patients than the carcinoids themselves.

Age Factors↗
PubMed1974

Surgical implications of portal venous system malformation.

The significance of congenital abnormalities in predisposing to portal hypertension and variceal haemorrhage needs to be remembered when these effects manifest in childhood, as portal venography will permit elucidation of the complicated congenital developmental abnormalities underlying the pathological condition and permit rational surgical amelioration.In the presence of portal hypertension the development of a collateral venous circulation may be represented by a hepatopetal or hepatofugal circulatory pattern and will closely parallel the developmental areas where portal and systemic venous circulations meet, being representative of the embryological anastomosis between the vitelloumbilical system and the posterior cardinal system of veins.

Angiography↗