Cloning and expression in Escherichia coli of a synthetic gene encoding the extracellular domain of the human muscle acetylcholine receptor alpha-subunit

To better define the antigenic sites on the human muscle acetylcholine receptor (AChR) that are involved in stimulating the production of pathogenic antibodies in myasthenia gravis (MG), the nucleotide sequence encoding the major extracellular domain of the AChR alpha subunit was chemically synthesized. The gene cassettes encoding amino acids (aa) 1-85 (AChR-I) and 86-210 (AChR-II), were cloned individually, and the coding sequence representing the complete major extracellular domain (aa 1-210; AChR-C) was obtained by subsequent fusion of cassettes encoding AChR-I and AChR-II. The genes were inserted into the inducible expression plasmid, pKK-223-3, and expressed in vitro and in vivo in Escherichia coli. Biological activity was demonstrated by immunoprecipitation of in vitro-synthesized AChR-C by sera from MG patients and by the alpha-bungarotoxin-binding activity of E. coli-synthesized AChR-II and AChR-C. The availability of the recombinant AChR polypeptides should facilitate studies on the molecular basis of the autoimmune response in MG.

Attitudes to clients with mental handicap

The increase in community care provision for people with a mental handicap makes an understanding of the attitudes and motivations of staff caring for them an urgent priority. Norma Raynes and colleagues describe a Department of Health-sponsored study which investigated the quality of care delivered in four key sectors of community residential care. Their findings reveal the positive attitudes of staff in all four settings and suggest that local authorities have a potential source of highly motivated recruits among those working in the health, voluntary and private sectors.

Quality assurance in home care: a diversified organization's approach

The rapid growth of home care brings with it greater risks and liabilities, making quality assurance increasingly more important. Home Health Services Foundation, Inc., a diverse, multi-corporate structure, developed an effective quality assurance program through communication and information sharing.

Transcriptional and post-transcriptional suppression of P450IIC11 and P450IIC12 by inflammation

Induction of inflammation in rats by treatment with endotoxin or turpentine is known to suppress levels of hepatic mRNAs for P450IIC11 and P450IIC12. We report that transcription of CYP2C12 in female rats is not significantly reduced from control levels; suppression of this gene during inflammation appears to be mediated post-transcriptionally. In contrast, transcription of CYP2C11 in male rats is reduced to 23% and to 5% of control levels by turpentine and by endotoxin, respectively. Sex-specificity of CYP2C11 expression is also regulated transcriptionally, whereas sex-specificity of CYP2C12 expression appears to be regulated by a post-transcriptional mechanism.

Adjuvant therapy for intracoronary stents. Investigations in atherosclerotic swine

Early thrombosis has complicated human stent implantation in several trials. To determine the best anticoagulation/antiplatelet therapy to maintain stent patency after percutaneous transluminal coronary angioplasty, we implanted the flexible balloon-expandable coil stent into the left anterior descending coronary artery of 28 atherosclerotic 8-month-old Hanford miniature swine. Animals were randomly assigned to one of three treatment groups: group A, aspirin (1 mg/kg/day) and dipyridamole (1 mg/kg three times a day); group B, aspirin and dipyridamole (same doses) plus Coumadin (dose required to prolong prothrombin time 1.3-1.5-fold that of normal); and group C, control. Adjuvant therapy was begun 3 days before stenting. Two pigs (one from group A and one from group B) died during implantation, both without thrombosis. Twenty-six animals survived until follow-up angiography and sacrifice at 1 month. No occlusive thrombosis of the stent occurred in survivors. Reduction of the stent lumen diameter was observed in every case at follow-up. Percent lumen reduction was 19% in group A, 26% in group B, and 24% in group C. Marked smooth muscle cell hyperplasia was seen by light and transmission electron microscopy at stent struts. Scanning electron microscopy of the luminal surface showed a variable morphology consisting of normal endothelium, adherent leukocytes, stellate periluminal cells, and occasional fibrin strands and red blood cells. Luminal narrowing was not affected by anticoagulation therapy, antiplatelet drugs, cholesterol level, or stent sizing. We conclude that occlusive thrombosis does not complicate stent implantation in this model but that substantial luminal narrowing due in part to smooth muscle hyperplasia does occur. The significance of luminal narrowing at the stent site requires further study.

Adequacy of disposable biopsy forceps for gastrointestinal endoscopy: a direct comparison with reusable forceps

Disposable plastic biopsy forceps were compared prospectively to reusable stainless steel forceps. Thirty consecutive patients underwent a total of 249 biopsies, 124 with the disposable forceps, and 125 with reusable forceps. Biopsy locations included the esophagus, stomach, small intestine, colon, and common bile duct. Specimens were compared microscopically to determine overall surface area, depth, adequacy, and diagnostic result. The disposable biopsy forceps yielded specimens which were 37% smaller when compared with the reusable forceps. In five of the comparisons, minor differences in histological findings were noted between the two groups of biopsy specimens, but these differences did not alter the pathological diagnosis. However, in three cases in which superficial specimens were obtained, an underlying carcinoma was missed with the disposable forceps. Our study documents the utility of disposable biopsy forceps for mucosal lesions. In addition, there were 11 mechanical failures in 38 biopsy attempts with the plastic biopsy forceps. These forceps appear to be limited in their capacity to obtain adequate specimens from firm tissue or when submucosal biopsy samples are required, and they will require refinements in design to duplicate specimen quality obtained by traditional reusable forceps. Disposable forceps are particularly suitable for biopsy of mucosal lesions in patients with possible communicable disease, and they should help to reduce cross-contamination in the gastroenterology laboratory.

Organic diseases mimicking atypical eating disorders

The authors present three case studies of patients referred to Children's Hospital and Medical Center, Seattle, Washington, for evaluation of possible eating disorders. The atypical manifestations of the cases warranted further investigation, which revealed an organic basis for their weight loss. The authors summarize the typical findings of bulimia and anorexia nervosa and discuss the clues from the case studies that mandated further evaluation.

Hepatic artery infusion and chemoembolization in the management of liver metastases

Hepatic metastases rather than the primary neoplasm usually dictate the course of the disease and patient's survival. For unresectable disease, intraarterial infusion of chemotherapy, embolization, and chemoembolization are viable alternatives. Intraarterial therapy for hepatic metastases is based on the dual blood supply of the normal liver (portal vein, 75%, and hepatic artery, 25%) and that of the tumors (hepatic artery, 90%). Intraarterial infusion delivers a higher concentration of chemotherapy, whereas chemoembolization adds ischemia and increased contact time with the tumor. Selective vascular occlusion for infusion, redistribution of the blood supply and pulsatile flow enhance the delivery of therapeutic agents to the liver.

Preclinical toxicity and pharmacology of liposome-entrapped cis-bis-neodecanoato-trans-R,R-1,2-diaminocyclohexane platinum(II)

Liposome-entrapped cis-bis-neodecanoate-trans-R,R-1,2-diaminocylohexane platinum(II) (L-NDDP) is a new lipophilic cisplatin derivative formulated in a liposomal carrier currently in phase I clinical trials. The preclinical toxicity and pharmacology of L-NDDP were studied in mice and dogs. At the LD50 dose (i.v. bolus) in mice (60.5 mg/kg or 181.5 mg/m2), a tenfold decrease in the granulocyte and platelet counts was observed in the absence of renal toxic effects. In dogs, the maximum tolerated dose (MTD) of L-NDDP given i.v. over a period of 45-60 min was 150 mg/m2. This dose produced significant vomiting (6-18 episodes), minimal renal dysfunction, a maximal decrease in granulocyte and platelet counts of from 30% to 70%, and acute and transient elevation of liver enzymes. Higher doses (225 and 300 mg/m2) resulted in severe gastrointestinal (GI) toxicity in one animal and the death of two others within 48 h. Autopsy results showed multifocal hemorrhages in the lungs, GI tract, kidney, and liver. Three dogs were treated monthly with the MTD up to a cumulative dose of 637.5-712.5 mg/m2 with excellent tolerance. No cumulative myelosuppression or liver dysfunction was observed, whereas a slight increase in the creatinine baseline level was detected in all three animals. Autopsy results at the end of the study showed mild changes limited to the liver, kidney, and GI tract. Pharmacologic studies showed that the drug was cleared, fitting a two-compartment model with a mean t1/2 alpha of 7.1 min and a t1/2 beta of 87.8 h. These studies show that L-NDDP can safely be given at therapeutic doses to animals and that the dose-limiting toxic effects consists of myelosuppression in mice and a multiorgan hemorrhagic syndrome related to vascular injury in dogs.