CART: from gene to function

CART was identified as a novel mRNA regulated by psychostimulant drugs. CART peptides appear to be neurotransmitters involved in a variety of functions such as feeding. The mouse gene has been characterized and localized to Chromosome 13. The processing of CART peptides is evident in Western blotting studies.     

Liver transplantation for metastatic hemangiopericytoma associated with hypoglycemia

We report a case of successful liver transplantation in a young man with metastatic hemangiopericytoma confined to the liver. He had a primary retroperitoneal hemangiopericytoma removed in 1982 and was diagnosed as having liver metastases 8 years later. Subsequently, he developed hypoglycemia, which did not respond to chemotherapy. Hepatectomy and transplantation resolved his hypoglycemic attacks. He remained well and symptom free for 4 years. Liver transplantation can provide effective palliation and should be considered in carefully selected patients with localized metastatic cancer.     

Sterilization and disinfection in general practice in Northern Ireland.

In view of the recent trend towards more minor surgery being carried out in general practice we decided to conduct a postal survey to assess the level of knowledge of sterilization and disinfection and the use of benchtop sterilizers in general practice in Northern Ireland. The survey, of all 366 practices in the Province, was carried out in January/March 1998. One hundred and eleven (30%) completed questionnaires were returned. All practices performed at least one of a range of procedures requiring sterilization or disinfection, e.g., minor surgery 95%, cervical smear taking 98%, syringing of ears 98%. Only 76% of practices had a benchtop sterilizer and 39% did not have access to a sterile supply department (SSD); 32% of the latter had no desire to utilize such a service. Only 25% and 34% correctly identified the Medical Devices Agency (MDA) definitions of sterilization and disinfection respectively. The MDA Device Bulletin on benchtop sterilizers had been read by only 26% of respondents. There was an 86% interest in attending a workshop on sterilization and disinfection. The concepts and practice of sterilization and disinfection appear not to be clearly understood. We conclude that resources must be identified to provide appropriate education in this important area for primary care staff.     

Clinical priorities. Points make prizes

Assessing patients for non-urgent surgery according to a numeric priority system has rationalised waiting times in three specialties in a pilot project. Traditional scoring systems result in little relation between urgency and waiting times. Enlisting doctors' support for a scoring system takes time.     

Normal visual development after unilateral complete ptosis at birth.

We report on a 5-year-old boy who was born with a unilateral complete ptosis secondary to a lid hematoma sustained at birth, which resolved spontaneously over the course of 6 weeks. Visual acuity and binocularity have developed normally. This case adds evidence to the proposal of a latent period before the onset of a sensitive period in visual development.     

Insulin delivery governed by covalently modified lectin-glycogen gels sensitive to glucose

A glucose-sensitive gel formulation containing concanavalin A and glycogen has been reported previously. Precipitation resulting from the addition of concanavalin A to glycogen has been documented, but the formation of glucose-sensitive gels based on lectin-glycogen interactions is novel and used here in our studies. An improved in-vitro self-regulating drug-delivery system, using covalently modified glucose-sensitive gels based on concanavalin A and a polysaccharide displacement mechanism, is described. The successful use of the covalently modified gels addresses a problem identified previously where significant leaching of the mitogenic lectin from the gel membranes of non-coupled gels was encountered. Concanavalin A was covalently coupled to glycogen by use of derivatives of Schiff's bases. The resulting gels, like the non-coupled gels, were shown to undergo a gel-sol transformation in response to glucose. Insulin delivery was demonstrated using this covalently modified system in conditions of repeated glucose triggering at 20 degrees C and 37 degrees C. The magnitude of the response was less variable than for the dextran-based gels studied previously. The performance of this system has been improved in terms of concanavalin A leaching. This could, therefore, be used as the basis of the design of a self-regulating drug-delivery device for therapeutic agents used to treat diabetes mellitus.     

Pre-oxygenation: an easy method for all elective patients

The transparent plastic facemask has been investigated as a pleasant method of pre-oxygenation for elective non-high risk cases in 60 healthy ASA I or II patients randomly allocated to two groups. The patients in the pre-oxgenated group (n = 30) received 8 litre min-1 oxygen through a plastic facemask for 3 min whereas those in a control group (n = 30) were not pre-oxygenated. In all patients anaesthesia was induced with propofol 2.5 mg kg-1, fentanyl 1 ug kg-1 and atracurium 0.6 mg kg-1. Manual ventilation of the lungs using a Mapleson A breathing system was performed for 2 min with 50% oxygen in nitrous oxide prior to oral intubation. Arterial saturation in the pre-oxygenated group rose significantly from a mean baseline value of 96.4 (+/- 0.9)% to 99 (+/- 0.8)% (P < 0.01) and then remained stable both after induction and intubation: 99.1 (+/- 0.8)% and 98.9 (+/- 1.1)% respectively. In the control group arterial saturation dropped sharply within 20 s following induction to a mean of 89.8 (+/- 3.1)%, and it was 30 s before arterial saturation reached the equivalent value in the pre-oxygenated group as a result of manual inflation of the lungs. An 8 litre min-1 oxygen flow via a standard transparent plastic facemask is a simple, feasible and acceptable method for routine pre-oxygenation for all elective cases.     

Responses of long descending propriospinal neurons to natural and electrical types of stimuli in cat

Long descending propriospinal (LDP) neurons (antidromically identified) having cell bodies of origin in the cervical enlargement and projecting axons at least as far as the L2 segment were studied. Extracellular recording of responses to natural and electrical stimuli was done in high-spinal cats.

(1) A receptive field for natural stimuli was found for 123 LDP neurons. An additional 108 LDP cells were not activated by the natural stimuli used, but some of these fired spike potentials in response to electrical stimulation of peripheral nerves of the forelimb. There was no distinction between neurons activated and those not activated by natural stimuli on the basis of location or conduction velocity.

(2) The most effective natural stimuli were mechanical manipulation of the skin (both low and high threshold), movement of joints of the paw, and pressure to the deep tissues, especially to the extensor side of the arm. These modalities of stimuli were most often excitatory, but could be inhibitory as well.

(3) On the basis of modality, 4 subgroups of LDP cells were identified: those which were responsive only to mechanical-cutaneous, joint-movement, or deep-pressure stimuli, and those which responded to several of these modalities of stimuli, the multimodal group. These subgroups could not be distinguished on the basis of conduction velocity.

(4) The receptive fields varied in size from small (one digit) to large (all of a forelimb). For single LDP cells they included ones with single and/or multimodal input from one or both forelimbs and various combinations of excitation and/or inhibition. However, those in the dorsal horn had only ipsilateral receptive fields, mainly of the mechanical-cutaneous type. Cells with bilateral receptive fields were mainly located medially in the ventral gray in laminae VII and VIII.

(5) A comparison of the location of the subtypes of LDP cells revealed that neurons activated by mechanical-cutaneous stimuli were in laminae I and IV–VIII; whereas deep-pressure and multimodal activated neurons were almost exclusively in laminae VII and VIII.

(6) LDP cells receiving input from deep-pressure receptors in the extensor muscles of the arm, joint-movement, or deep-pressure receptors of the paw probably relay position or weight-bearing information about the forelimbs to the lumbosacral spinal cord. This arrangement suggests that LDP neurons function in interlimb coordination and would be active during locomotion. They probably participate also in other reflexes elicited by cutaneous and deep stimuli.