Inhibitors of tripeptidyl peptidase II. 2. Generation of the first novel lead inhibitor of cholecystokinin-8-inactivating peptidase: a strategy for the design of peptidase inhibitors

The cholecystokinin-8 (CCK-8)-inactivating peptidase is a serine peptidase which has been shown to be a membrane-bound isoform of tripeptidyl peptidase II (EC 3.4.14.10). It cleaves the neurotransmitter CCK-8 sulfate at the Met-Gly bond to give Asp-Tyr(SO(3)H)-Met-OH + Gly-Trp-Met-Asp-Phe-NH(2). In seeking a reversible inhibitor of this peptidase, the enzymatic binding subsites were characterized using a fluorimetric assay based on the hydrolysis of the artificial substrate Ala-Ala-Phe-amidomethylcoumarin. A series of di- and tripeptides having various alkyl or aryl side chains was studied to determine the accessible volume for binding and to probe the potential for hydrophobic interactions. From this initial study the tripeptides Ile-Pro-Ile-OH (K(i) = 1 microM) and Ala-Pro-Ala-OH (K(i) = 3 microM) and dipeptide amide Val-Nvl-NHBu (K(i) = 3 microM) emerged as leads. Comparison of these structures led to the synthesis of Val-Pro-NHBu (K(i) = 0.57 microM) which served for later optimization in the design of butabindide, a potent reversible competitive and selective inhibitor of the CCK-8-inactivating peptidase. The strategy for this work is explicitly described since it illustrates a possible general approach for peptidase inhibitor design.

Prevalence of Onchocerca volvulus nodules in the Sankuru River Valley, Democratic Republic of the Congo, and reliability of verbal assessment as a method for determining prevalence

The epidemiology of onchocerciasis in much of the Democratic Republic of the Congo (formerly Zaire) is not well established. We report the results of an onchocerciasis rapid assessment survey carried out in 18 villages of the Sankuru River Valley in the central part of this country in preparation for mass distribution of ivermectin. Thirty men from each village were randomly selected and examined for subcutaneous nodules. The prevalence of nodules among these men in each village ranged from 82.5% to 100% with a mean prevalence of 95.0%. This study also assessed the validity of using verbal assessment instead of physical examination to determine prevalence of nodules. This verbal method had a sensitivity of 93.5% and a specificity of 83.3%. High sensitivity and specificity for this method suggest that it might be a cost-effective approach to determine the prevalence of onchocerciasis over large areas without using physical examinations requiring medical personal. This approach could be particularly useful where the coverage of health services is poor. The use of the Global Positioning System made it possible to send coordinates and survey data electronically to World Health Organization personnel in Geneva for computer generation of prevalence maps. The use of river boats to conduct surveys and support ivermectin distribution in the Congo is discussed.

A medical audit and patient survey of hysterectomies performed for menstrual disorders

The aim of the study was to carry out an audit of 283 hysterectomies performed for menstrual disorders over a one year period, and to determine the satisfaction of the women concerned towards their treatment. The medical records of these patients were examined, and they were each sent a questionnaire, 69% of which were completed and returned. The most common presenting symptoms were menorrhagia and dysmenorrhoea. In 53% of cases no clinical abnormality was postulated and in 31% of cases no pathological abnormality was found. The preoperative clinical and pathological diagnoses were in agreement for 59% of patients. Over 90% of women were satisfied with the management of their case by their GP and the gynaecology outpatient clinic. The use of patient-controlled analgesia systems was associated with better post-operative pain relief than intramuscular injections. Thirteen percent of patients required blood transfusion; 21% suffered some form of postoperative complication, most of which were minor. Ninety-four percent of the women were pleased that they had undergone hysterectomy, and 76% wished that they had had the operation sooner. It was concluded that hysterectomy is perceived positively by patients and should not necessarily be considered as a last resort treatment for menstrual disorders.

An evaluation of purified reconstituted type 1 collagen fibers

Collagen fibers composed of type I collagen molecules were studied for biocompatibility and mechanical properties. These fibers were crosslinked using two different processes: 1) glutaraldehyde, 2) dehydration followed by exposure to cyanamide (DHT/C); the latter method produces only urea as a by-product of the crosslinking process and is postulated to be more biocompatible. An in vitro model using rat tendon fibroblasts growing on individual fibers was used to evaluate outgrowth rates, cell/fiber interactions, and cell morphology. These studies showed an advantage with DHT/C crosslinking, relative to glutaraldehyde crosslinking, in promoting fibroblast growth. In vivo intramuscular implantation in rats showed excellent biocompatibility for both kinds of collagen implants. In addition, aligned ingrowth into the implant from the medial collateral ligament when applied in that location was demonstrated. Mechanical testing demonstrated the higher strength of dry fibers; however, upon hydration, there was a marked decrease in stress to failure. This reduction in strength was due principally to an increase in cross section due to swelling. These collagen fibers appear to be very biocompatible even in the presence of low concentrations of glutaraldehyde. They promote fibrous aligned ingrowth in a setting of ligament healing. Thus, they represent a strong candidate as a scaffold ligament or tendon prosthesis if crosslink density can be increased.

Autotransfusion in revision total hip arthroplasties using uncemented prostheses

During the period from March 1983 to April 1987, autotransfusion was used in 64 patients treated with cementless revision total hip arthroplasties. An average of 3.9 units of intraoperative blood was salvaged, using a semicontinuous system; 6.5 units were salvaged in patients requiring segmental grafting of the acetabulum and femur. Patients not requiring segmental grafting had only 2.1 units salvaged. The use of homologous banked blood in patients without stored autologous units available was almost three times that of patients with autologous blood. Autotransfusion in the form of autologous transfusions and intraoperative blood salvage accounted for 72% of the total blood requirements. The cell saver is most cost-effective in patients with femur and acetabular bone loss requiring segmental grafting. An autologous transfusion program is important in all patients in whom blood transfusions are expected.

Trauma operating room in conjunction with an air ambulance system: indications, interventions, and outcomes

We report a retrospective study of 198 trauma patients brought directly to a trauma operating room by an air ambulance system. Despite rapid transport, expert prehospital resuscitation, and the capability of early surgical intervention, the overall mortality was high (57%). There was no significant salvage of patients arriving without pulse, blood pressure or cardiac activity. Optimal trauma care failed to show encouraging results in this preselected group of patients with predominantly blunt and multisystem injury. The justification and cost effectiveness of this system of trauma care is discussed.