Deep-freezing versus 4 degrees preservation of avascular osteocartilaginous shell allografts in rats

Osteocartilaginous allografts (distal femurs of rats) were stored at 4 degrees for six, 12, 24, and 48 hours and at -80 degrees for five days and then evaluated for viability of the bone and cartilage. Storage at 4 degrees for 12 or 24 hours had little effect on cartilage viability but decreased bone viability to 40% and 10% of controls, respectively. Storage at -80 degrees for five days resulted in nonviable bone in all cases but showed an either/or response of cartilage, with high viability in two cases and nonviability in the other eight cases. In a second set of experiments, femurs from rats were stored in situ at 4 degrees for 12 or 24 hours or were harvested and stored at -80 degrees for five days, after which they were transplanted into rats of a different strain. The antibody response to each set of femurs was measured at two, six, and 12 weeks after operation. The 4 degrees storage resulted in a moderately decreased immunogenicity, whereas the storage at -80 degrees resulted in significantly reduced immunogenicity.     

Measurement of oxygen uptake in the non-steady-state

The purpose of these experiments was to develop and validate an open-circuit technique for measurement of gas exchange during the transition from rest to constant load steady-state exercise. The design of the open-circuit system employed to measure gas exchange in these experiments used a mixing chamber to collect the subject's expired ventilation where fractions of O2 and CO2 were determined via electronic gas analyzers. A gasometer was used to measure inspired ventilation and the analog signals from the two gas analyzers and the gasometer were sent to a microcomputer for computation of VO2. In calculating VO2, the mixed expired gas concentrations were matched with ventilatory volume using a previously determined time delay. To determine the validity of the open-circuit system, four subjects performed a series of 16 rest-to-work transitions on a cycle ergometer. In eight of the experiments, serial measurements of VO2 were obtained every 20 s for 3 min using the open-circuit mixing chamber system while the additional eight experiments used the Douglas bag technique. No significant difference (p greater than 0.05) existed between VO2 values calculated by the two techniques. Mean differences in VO2 between the two techniques during the first three 20-s measurement periods were 6, 53, and 63 ml, respectively. Using the Douglas bag technique as the standard, this represents a relative measurement error of 0.1%, 4.5%, and 3.6%, respectively, at the above time intervals. These data demonstrate that an open-circuit system employing a mixing chamber and the appropriate time delay to match expired gas fractions and ventilation is a sensitive means of measurement of VO2 in the non-steady-state.     

Administration to humans of ORG 21465, a water soluble steroid i.v. anaesthetic agent

Ten male volunteers received a 1-min i.v. infusion of a new water soluble steroid anaesthetic agent, ORG 21465. Individuals received doses ranging from 0.8 to 1.8 mg kg-1. All subjects experienced venous pain at the site of injection; those receiving 1.0 mg kg-1 or more became anaesthetized. There was no evidence of histamine release and apnoea did not occur. Excitatory phenomena were observed in all subjects and were dose related; no spikes were seen on the EEG. Pharmacokinetic analysis supported a three-compartment (non-weight- related) model with compartmental volumes V1, V2 and V3 of 4.31, 14.2 and 89.4 litre, respectively. Clearance from the central compartment V1 was 1.55 litre min-1. Inter-compartmental clearances Q1 and Q2 were 2.54 and 1.79 litre min-1. We found that ORG 21465 was an effective anaesthetic in humans. The relationship between sedation, anaesthesia and excitation requires further exploration.      

RETROPERITONEAL SCHWANNOMA: A CASE SERIES AND REVIEW

Schwannomas account for only a small percentage of retroperitoneal tumours. Presentation is typically varied and non-specific and pre-operative diagnosis is difficult. Herein are described five cases of retroperitoneal schwannoma. Presentation was varied, ranging from abdominal pain, abdominal mass, obstructed labour or an incidental finding. All patients had either an abdominal computed tomography scan and/or ultrasound performed. Pre-operative biopsy either by fine needle aspiration (in one patient) or core biopsy in two patients was unhelpful. In four patients with smaller tumours, complete excision was possible with no apparent long-term morbidity and no clinical evidence of recurrent tumour with follow up from 3.5 months to 11 years. For the largest tumour, complete surgical excision was not attempted as it would have entailed significant morbidity.     

Transjugular percutaneous inoue balloon mitral commissurotomy in a patient with inferior vena cava obstruction after liver transplantation.

Percutaneous transvenous mitral commissurotomy was performed successfully via the transjugular approach in a patient with severe rheumatic mitral stenosis and obstruction of the inferior vena cava due to prior liver transplantation. This case demonstrates the advantage of the jugular approach in patients with difficult anatomy.     

Asynchronous pre- and postsynaptic activity induces associative long-term depression in area CA1 of the rat hippocampus in vitro.

Associative long-term depression (LTD) was induced in hippocampal slice cultures with repeated low-frequency (0.3 Hz) stimulation of the Schaffer collateral pathway, only when such stimuli were preceded by intracellular injection of brief depolarizing current pulses in the postsynaptic CA1 pyramidal cell. The decrease in excitatory postsynaptic potential amplitude lasted > 30 min, could be reversed by induction of potentiation, could be induced at previously potentiated inputs, was input-specific, and did not require activation or potentiation of other inputs. The magnitude of the depression depended upon the time interval between depolarization and stimulation and upon the duration of the depolarization pulse. LTD was not observed in neurons impaled with electrodes containing a Ca2+ chelator. LTD could not be induced in the presence of an N-methyl-D-aspartate receptor antagonist, suggesting that voltage-dependent Ca2+ influx is necessary but not sufficient for LTD induction. We conclude that associative LTD results when synaptic activity follows postsynaptic depolarization within a circumscribed time window.     

Reoperation in patients with the short bowel syndrome.

The clinical courses of 53 adult patients with the short bowel syndrome (SBS) were evaluated to determine the incidence of and indications for reoperation. Mesenteric vascular disease (23 patients) and malignancy/irradiation (18 patients) were the most frequent causes of resection. Early reoperation was necessary in nine (17%) patients, primarily for intestinal complications. Twenty (53%) of the 38 patients leaving the hospital required a later abdominal procedure during the mean follow-up of 30 months (range: 2 to 108 months). Three (33%) of nine patients with ulcer disease had gastric resection. Six (21%) of 28 patients at risk for cholelithiasis developed symptoms. Four of these patients underwent cholecystectomy, and three others had a prophylactic cholecystectomy. Ten patients underwent ostomy closure or formation. Intestinal disease necessitated stricturoplasty (three), serosal patch (one), minimal resection (three), or takedown of an ileal conduit (one). Twenty-four (63%) of 38 patients with SBS received home total parenteral nutrition for a mean of 22 months (range: 2 to 105 months). Eleven patients required more than 1 vascular access procedure, and 4 had more than 3 procedures. Patients with the SBS frequently require reoperation for intestinal conditions, cholelithiasis, peptic ulceration, and vascular access. Prophylactic cholecystectomy and strategies for preserving intestinal length are important considerations in these patients.