Wet extrusion of fibronectin-fibrinogen cables for application in tissue engineering.

A method for the wet extrusion of human plasma-derived fibronectin-fibrinogen cables is described. Solutions of fibronectin and fibrinogen with and without sodium alginate and carboxymethylcellulose (CMC) are tested. The rheological properties of the protein solutions changed from Newtonian to shear thinning non-Newtonian in the presence of small quantities of these additives, the apparent viscosity increased, and the extrusion properties of the protein solutions improved. Cables were prepared using a capillary with a diameter of 1 mm and overall length of 18 mm. Cable diameter was reduced to about 0.5 mm by drawing using a series of rollers. Cables prepared with sodium alginate were found to have suitable properties, and those made with CMC were sticky and difficult to handle. Solutions containing no sodium alginate required a minimum total protein concentration of about 70 mg/mL for extrusion. Extruded cables were prepared with solutions containing 140 mg/mL total protein with 12.9 mg/mL alginate (high protein), and 46 mg/mL total protein with 47.6 mg/mL of sodium alginate (high alginate). The mechanical strength of the extruded cables was within the range suitable for application in tissue engineering. Extrusion of the protein solutions into cables was achieved in a coagulation bath. Cables with a mechanical strength of approximately 30 N/mm(2), suitable for wound repair and nerve regeneration applications, were prepared with a coagulation bath containing 0.25 M HCl, 2% CaCl(2) at a pH of <0.9. These cables also had a large average elongation at break of 52%, and showed an increase in cable length after breakage (permanent set) of 20%, demonstrating the potential for drawing the cables down to a fine diameter.

Direct communication with general practitioners improves management of infants at risk of hepatitis B.

The National Screening Committee has recommended that all women presenting for antenatal care be offered routine screening for hepatitis B by the year 2000. In a low prevalence area a survey of the management of neonates whose mothers were positive for hepatitis B surface antigen showed that management of this group was better among general practitioners who had received advice on treatment.

Haemosuccus pancreaticus due to mucinous cystadenocarcinoma: the significance of recurrent abdominal pain, hyperamylasaemia and a pancreatic cyst in association with recurrent gastrointestinal bleeding.

Haemosuccus pancreaticus is a rare cause of gastrointestinal haemorrhage, and when it presents in otherwise healthy people, can prove difficult to diagnose. The cardinal features are episodic epigastric pain associated with a raised serum amylase and the passage of melaena. Failure to make the connection between recurrent gastrointestinal bleeding and apparently unrelated symptoms attributable to pancreatitis may lead to a significant delay in diagnosis.

A comparison of Fleet Phospho-soda with Picolax in the preparation of the colon for double contrast barium enema.

This study was performed to compare the patient acceptability and the efficacy of two different agents for bowel preparation prior to double contrast barium enema. One-hundred and ninety-four outpatients were randomized to have either two sachets of Picolax or two bottles of Fleet Phospho-soda and restricted to clear fluids on the day prior to their examination. Patients answered a short questionnaire before their enema. The decubitus films were assessed for faecal residue and bowel coating by three observers blinded to the type of preparation used. There was no significant difference in faecal residue nor in the bowel coating between the preparations. However patients found Picolax significantly easier to take, being better tasting and provoking less nausea and vomiting than Fleet Phospho-soda.

Choledocholithiasis associated with malignant biliary obstruction--significance and management.

Distal bile duct stones and proximal extra-hepatic malignant biliary obstructions may coexist. These stones, probably predating the development of the malignant obstruction but of unknown aetiological significance, were found in seven of 60 patients with proximal tumours (11.6%) at percutaneous biliary drainage. In two of these cases, stones blocked outflow from a supra-ampullary stent. All seven patients also had evidence of gall-bladder stones. Five of the seven patients had cholangiocarcinoma, giving an incidence of duct stones in such patients (n = 27) of 18.5%. In one case, the stones were removed endoscopically, in four, the stones were removed percutaneously and, in the remaining two cases, they were left in situ beside a stent. None of 120 cases with malignant obstruction had stones proximal to the obstruction. Distal common duct stones are associated with proximal malignant biliary duct obstruction, especially with cholangiocarcinoma and coexisting gall-bladder stones. They may interfere with stent function and cause diagnostic confusion at cholangiography.

Colorectal cancer surgery in a district general hospital.

The purpose of our study was to audit colorectal cancer surgery in a large district hospital, compare our results with other series and highlight any areas in patient management where improvements could be made. A comprehensive audit was undertaken of all patients undergoing surgery for colorectal adenocarcinoma over a 2-year period (December 1989 to November 1991). Two hundred and twenty-two patients were studied. General practitioner referrals were seen within 8 weeks in 140 (96%) of 149 cases. Delay to diagnosis was associated with barium enema examination. A consultant or senior registrar was present at 187 (84.2%) of operations, and only two (0.9%) were undertaken between 24.00 and 08.00 hours. For rectal tumours the ratio of anterior resection to abdomino-perineal excision was 2:1. Eight of nine anastomotic leaks followed low anterior resection. All required re-operation and three died. The overall in-hospital mortality was 17 (7.7%). Although our results compare favourably with other published series, several areas for potential improvement in management have been identified.

Should nurses be allowed to request X-rays in an accident & emergency department?

A prospective study was carried out during the month of November, 1990 in the A&E Department, St John's Hospital, Livingston in order to assess the extended role of the A&E nurse and their ability to request X-rays prior to patients being seen by a doctor. A total of 579 randomly selected patients were triaged by A&E Department nurses. Almost 3/4 of these patients were X-rayed at the request of the triage nurse. Less than 7% of these X-rays were considered to have been unnecessary by the doctor who subsequently managed the patient. Of those patients who had an X-ray after seeing a doctor, more than 90% fell within the X-ray triage criteria but had not had an X-ray requested by the triage nurse. Overall, nurses were shown to request X-rays correctly and efficiently with the result that patients had to spend less time in the A&E Department.

Pilomatrixoma as a diagnostic problem: the Edinburgh experience.

The purpose of this retrospective study was to review the paediatric experience in Edinburgh of a relatively benign skin tumour. The study group consisted of children less than 13 years of age with a pathological diagnosis of pilomatrixoma over the period between January 1980 and December 1989. The results reaffirmed a female preponderance. The majority of lesions had been present for less than 1 year at the time of removal but were mainly misdiagnosed at the time of primary consultation or at removal. Although pilomatrixoma has a 'typical' appearance pathologically there are problems with preoperative diagnosis. Sites of occurrence are comparable with the dermoid type of cyst and the possibility must be considered of an embryological origin for pilomatrixoma.

Use of plasma protein fractions as serum substitutes for in vitro cell culture.

Fractions produced during routine production of human plasma protein concentrates using cold ethanol precipitation have been tested for their ability to support animal cell growth in vitro. A mouse-mouse hybridoma cell line, ES-6, which secretes a monoclonal antibody (mab) to human group A red blood cell antigen, has been used as a model. Fraction 4-1 protein has been found to be effective at 0.5-1.0 g/l in RPMI 1640 and has supported growth of ES-6 for 18 months, both growth and mab. production being comparable with that achieved in 10% foetal calf serum. Fraction 4-1 protein has been shown to contain albumin, transferrin, alpha-1 antitrypsin and immunoglobulin. It is reported to be a source of somatomedin C. The immunoglobulin content can be reduced. Other mouse and rat hybridomas, human mab. producing lymphoblastoid cells, Namalva and HEP-2 cells have grown well in medium supplemented with Fraction 4-1 protein.

The accumulation of lactic acid and its influence on the growth of Plasmodium falciparum in synchronized cultures.

Synchronization of Plasmodium falciparum cultured in vitro results in a one-step growth pattern that allows the study of stage-specific metabolic activities of the parasites. Lactic acid (LA) was selected as a metabolic marker, and the concentration of this end product found in spent media was correlated with the different erythrocytic stages of the parasites. When the medium was changed at 12 h intervals, cultures containing predominantly trophozoites produced 3.66 +/- 0.55 mumol LA per 12 h per 10(7) parasitized cells (n = 26), an amount of LA that is about 8 to 20 times higher than that found in corresponding cultures containing predominantly ring forms. Depending on the stage of development, parasitized red blood cells produced between 5 and 100 times more LA than uninfected erythrocytes (3.72 +/- 0.62 mumol LA per 12 hours per 10(9) red blood cells) (n = 41) when cultured under identical conditions. The intraerythrocytic development of the parasites was not impaired by exposure to extracellular concentrations of LA up to 12 mM over a 12 h period. The growth resulting in such cultures was described as uninhibited and was characterized by a multiplication index of 10 or higher. Above the threshold of 12 mM of LA, progressive inhibition of parasite development occurred. The stage-specific LA production reported can be used to predict the amount of LA that will have accumulated at the end of a subsequent 12 h incubation period during synchronized in vitro growth of Plasmodium falciparum. Using these values, it is possible to establish an optimal medium exchange schedule, thereby assuring uninhibited growth and a correspondingly high parasite yield.

Plasmodium falciparum: modifications of the in vitro culture conditions improving parasitic yields.

We attempted to optimize some of the variables involved in the in vitro culturing of Plasmodium falciparum. Irrespective of the isolates used, suspension cultures in glucose-enriched RPMI-1640 medium buffered with TES yielded about twice the amount of parasites than could be obtained from static, thin-layer cultures with HEPES-buffered RPMI-1640 without additional glucose. In suspension cultures, methylcellulose (1 mg/ml) was added to protect the erythrocytes. In addition the erythrocytes were found to be more suitable for culturing P. falciparum when stored as a concentrate in saline-adenine-glucose than as whole blood in citrate-phosphate-dextrose. With a cloned isolate of P. falciparum (Tak9/clone 96) a further stimulation of the final parasitemia could be achieved by supplementing the medium with hypoxanthine (50 micrograms/ml) and reduced glutathione (600 micrograms/ml). Moreover, we identified hypoxanthine and glutathione as two of the factors critical for the ability of human serum to support the growth of the parasites. These modifications give a two- to four-fold increase in the final parasitemia over the original Trager-Jensen culture method, thus allowing more parasites to be isolated for biochemical studies.

Cardiac function in end-stage renal disease.

To assess cardiac status in end-stage renal disease, we compared clinical, ECG, and echocardiographic data from 37 patients on maintenance hemodialysis with data from 42 patients with functioning renal transplants. Cardiovascular symptoms and abnormal cardiovascular findings were more common in dialysis-maintained patients than in those with transplants. Follow-up studies indicated that despite a high prevalence of cardiac symptoms, abnormal physical signs, and dilated left ventricles among patients with end-stage renal disease, systolic left ventricular function was generally well preserved irrespective of renal failure therapy. Compared with maintenance hemodialysis, however, successful renal transplantation is associated with an overall enhancement of cardiac status, the majority of which is probably secondary to transplant-associated improvement in hemoglobin level and control of intravascular volume.