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Biomedical subjects

A D Stephens

Publications and source records attributed to A D Stephens.

At least 19 recordsLinked to original sources
PubMed1995

Cancer recurrence following laparoscopic colectomy. Report of two patients treated with heated intraperitoneal chemotherapy.

PURPOSE: Use of laparoscopic techniques for resection of colon and rectal cancer has raised considerable controversy. There is increasing concern that wound recurrence and peritoneal dissemination may represent a potentially fatal complication of this technique. METHODS: The surgical literature was reviewed, and clinical course of two patients is presented. RESULTS: Our two patients had tumor recurrence in the laparoscopy port sites within one year after laparoscopic assisted colectomy for Dukes B adenocarcinoma of the colon. At laparotomy, diffuse peritoneal carcinomatosis without lymph node or liver metastases were found in both patients. They were treated by surgical resection of recurrent disease combined with heated intraoperative intraperitoneal mitomycin C chemotherapy and five days of early postoperative intraperitoneal 5-fluorouracil. These patients are clinically free of disease at 1.5 years after treatment of peritoneal implants. CONCLUSIONS: Cancer recurrence in abdominal wall incisions after laparoscopic colectomy has been reported in an increasing number of patients. It is possible that this technique should be abandoned. Cytoreductive surgery combined with intraperitoneal chemotherapy may represent the most adequate treatment of recurrent cancer that occurs following laparoscopic colectomy.

Adenocarcinoma↗
PubMed1995

Intraaortic stop-flow infusion: pharmacokinetic feasibility study of regional chemotherapy for unresectable gastrointestinal cancers.

BACKGROUND: This study attempted to increase the exposure of gastrointestinal tract tissues to chemotherapy by prolonging the first pass of intraaortically administered drug by temporary occlusion of vascular structures. METHODS: Bolus infusion of 14C-labeled mitomycin C (MMC) mixed with unlabeled MMC was performed in dogs. Distribution of MMC in gastrointestinal tract tissues was studied under different types of major vessel occlusion. Three dogs with intravenous infusion constituted the control group. Vascular flow was controlled in four ways for 30 min: type I--stop-flow infusion (SFI) with clamping of the abdominal aorta above the celiac and below inferior mesenteric artery; type II--with additional clamping of the inferior vena cava above the diaphragm; type III with additional clamping of the portal vein in the hepatoduodenal ligament; and type IV--with surgical exclusion of nongastrointestinal branches of the aorta in addition to type II clamping. RESULTS: Type II and IV produced a 3-10-fold increase in exposure to MMC of major gastrointestinal tissues as compared with intravenous infusion. Area under the curve ratios with type IV were most prominent in the following tissues: stomach, pancreas, liver, and mesenteric lymph node. CONCLUSION: Access of MMC to several gastrointestinal tissues was increased through SFI. Type IV infusion was the most effective. Tissue exposure to MMC was especially advantageous for stomach, pancreas, liver, and mesenteric lymph node.

Animals↗
PubMed1992

Enhanced platelet reactivity and hypercoagulability in the steady state of sickle cell anaemia.

A prospective controlled study was undertaken to investigate the haemostatic and coagulation status of 18 adult subjects in the steady state of sickle cell anaemia (SCA), using a relatively new in vitro technique. Shear induced haemostasis, whole blood dynamic coagulation, and spontaneous thrombolysis were measured using nonanticoagulated blood. As expected, the haemoglobin levels were significantly lower and platelet counts significantly higher in subjects with SCA compared with controls. Haemostasis and coagulation were significantly enhanced in SCA. No correlation was found between the raised platelet count and enhanced haemostasis or the reduced haemoglobin and hypercoagulation, respectively. Hyperactivity of the haemostatic system may have a pathogenic role in vaso-occlusive microthrombotic events and in the leg ulcers, both of which occur frequently in SCA.

Adolescent↗
PubMed1989

Cystinuria and its treatment: 25 years experience at St. Bartholomew's Hospital.

Cystinuria is an inherited condition affecting the active transport of the diamino acids cystine, ornithine, lysine and arginine across the renal tubule and the small intestine. The only clinical effect is the production of urinary tract stones and if these can be prevented the affected individuals can lead a normal life. In many people cystine stones can be dissolved and new stone formation prevented by a high fluid intake, but if this does not succeed regular treatment with penicillamine will do so. Although many side-effects have been described with penicillamine treatment it is rare for them to be severe enough to prevent its use in patients with cystinuria. Since the clinical effects of cystinuria can be prevented by either a high fluid intake or by penicillamine it is important to make the diagnosis in affected individuals as soon as possible and cystinuria should therefore be considered in all people (regardless of age) who form urinary stones.

Cystinuria↗
PubMed1989

Sickle cell trait.

Explore the source record for details and available documents.

Anemia, Sickle Cell↗
PubMed1985

A distant gene deletion affects beta-globin gene function in an atypical gamma delta beta-thalassemia.

We describe an English family with an atypical gamma delta beta-thalassemia syndrome. Heterozygosity results in a beta-thalassemia phenotype with normal hemoglobin A2. However, unlike previously described cases, no history of neonatal hemolytic anemia requiring blood transfusion was obtained. Gene mapping showed a deletion that extended from the third exon of the G gamma-globin gene upstream for approximately 100 kilobases (kb). The A gamma-globin, psi beta-, delta-, and beta-globin genes in cis remained intact. The malfunction of the beta-globin gene on a chromosome in which the deletion is located 25 kb away suggests that chromatin structure and conformation are important for globin gene expression.

Adult↗
PubMed1976

Cystinuria: a new genetic variant.

1. A family is reported with an unusual type of cystinuria. 2. The propositus presented with a cystine renal stone; the renal tubular reabsorption of cystine was grossly abnormal but the tubular reabsorption of ornithine, lysine and arginine was only slightly less than normal. 3. One of the children of the propositus escreted cystine and lysine in increased amounts typical of type II heterozygotes for cystinuria. 4. The renal transport defect in this family may represent one end of the spectrum of cystinuria or it may be a form akin to isolated hypercystinuria.

Amino Acids↗
PubMed1975

Haemoglobin Rahere (beta Lys-Thr): A new high affinity haemoglobin associated with decreased 2, 3-diphosphoglycerate binding and relative polycythaemia.

A new haemoglobin with increased oxygen affinity, beta82 (EF6) lysine leads to threonine (Hb Rahere), was found during the investigation of a patient who was found to have a raised haemoglobin concentration after a routine blood count. The substitution affects one of the 2, 3-diphosphoglycerate binding sites, resulting in an increased affinity for oxygen, but both the haem-haem interaction and the alkaline Bohr effect are normal in the haemolysate. This variant had the same mobility as haemoglobin A on electrophoresis at alkaline pH but was detected by measuring the whole blood oxygen affinity; it could be separated from haemoglobin A, however, by electrophoresis in agar at acid pH. The raised haemoglobin concentration was mainly due to a reduction in plasma volume (a relative polycythaemia) and was associated with a persistently raised white blood count. This case emphasises the need to measure the oxygen affinity of haemoglobin in all patients with absolute or relative polycythaemia when some obvious cause is not evident.

Adult↗
PubMed1975

A study of the renal handling and intestinal absorption of dibasic amino acids in a patient with genotype +/11 heterozygous cystinuria and idiopathic hypercalcuria.

A case is reported of a patient with idiopathic hypercalcuria who was referred for investigation of renal calculi. Studies of urinary amino acid excretion in the patient and all living members of his family, as well as studies of endogenous renal clearances of dibasic amino acids and cystine in the patient and his daughter, indicated that the patient had genotype +/11 heterozygous cystinuria. Intestinal perfusion studies showed however that the patient was able to absorb L-lysine, L-arginine normally from the jejunum and ileum. This suggests that a difference exists between renal and intestinal handling of lysine and arginine in cystinuria.

Adult↗