Sensitization of CD4+ T cells to coagulation factor VIII: response in congenital and acquired hemophilia patients and in healthy subjects.

Antibodies (Ab) that inhibit factor VIII (fVIII) may develop in patients with hemophilia A and rarely in individuals without congenital fVIII deficiency (acquired hemophilia). Synthesis of fVIII inhibitors requires CD4+ T cells. We investigated the proliferative response of blood CD4+ cells from 11 patients with congenital or acquired hemophilia and 12 healthy subjects, to recombinant human fVIII, and to pools of overlapping synthetic peptides spanning the sequences of individual fVIII domains. All patients had CD4+ cells that responded to fVIII. The intensity of the responses fluctuated over time: several patients had brief periods when they did not respond to fVIII. All healthy subjects had transient CD4+ responses to fVIII, that were significantly lower than those of hemophilia patients. Also, healthy subjects responded to fVIII less frequently and for shorter periods than hemophilia patients. All patients and healthy subjects recognized several fVIII domains: the A3 domain was recognized most strongly and frequently. The transient sensitization of CD4+ cells to fVIII in healthy subjects suggests that inadequate tolerization of CD4+ cells to fVIII, due to lack of endogenous fVIII, is an important factor in the development of clinically significant anti-fVIII antibodies in hemophilia A.

A new replacement for small vessels.

A new modification of the mandril-grown vascular prosthesis appears to combine the best features of presently available synthetic vascular replacement materials. Glutaraldehyde-tanned polyester mesh-supported conduits (diameters 4, 6, and 8 mm) grown in the subcutaneous tissue of sheep, maintain 100% patency in the aortic, aortoiliac, and common iliac positions of canine recipients for over 2 years. One-millimeter diameter grafts placed in the infrarenal abdominal aorta of rat recipients were patent in 72% for 6-month follow-up periods. The grafts maintained a modicum of antigenicity despite tanning, as evidenced by the slightly elevated hemagglutination (0 to 2 dilutions) titers against sheep red blood cells in ovine graft recipients and the accelerated rejection of the donor strain skin grafts in Fischer rats receiving Brown-Norway conduits. Finally, in a limited clinical study, 21 of 24 femoropopliteal and three of three femoroposterior tibial grafts remained patent in short follow-up periods (2 to 16 months). Two aortocoronary bypass grafts have continued to function in one patient for 19 months. Minimal inflammatory reaction and no aneurysmal degeneration were found in the material studied.

Glutaraldehyde-tanned ovine collagen conduits as vascular xenografts in dogs: a preliminary report.

Collagen tubes grown in sheep around Silastic mandrils were tanned in neutral, buffered glutaraldehyde and deployed as arterial xenografts in the aorta of dogs. The grafts maintained patency for up to three years and did not show any signs of aneurysmal dilation or luminal narrowing. The lumen became lined with a neointima, and host collagen was deposited around the periphery so that the thickness of the wall of the graft approximated that of the aorta.

Minute vascular replacements.

Glutaraldehyde-tanned, mesh-reinforced, mandrel-grown ovine collagen conduits were compared with tanned human umbilical arteries and polytetrafluoroethylene (PTFE) grafts in the aorta of rat recipients. All grafts had 100% patency and became lined by a cellular neointima. The mean maximum thickness of the neointima of the tanned human umbilical artery, ovine collagen graft, and the PTFE grafts was 68, 57, and 13 micrometer, respectively. Neointimal proliferation was complete for the two biosynthetic grafts, but none was seen in the center of the PTFE grafts as late as ten weeks. The mean increase in lumen cross-sectional area was 49% for the umbilical artery grafts, 23% for ovine collagen conduits, and 4% for the PTFE grafts. Longer follow-up periods will be required before unqualified support can be given to clinical trials of these small-diameter prostheses; however, long-term patency for synthetic grafts of such a small caliber is encouraging for future microvascular applications and for study of host-prosthesis interactions.

Foreign body obstruction of the small colon in six horses.

Six horses, which had a foreign body obstruction of the small colon showed abdominal pain of progressing severity and intestinal tympany. On rectal examination the caecum and large colon were distended with ingesta and gas but the obstructing mass could be palpated in only 3 cases. All horses had elevated indirect blood pressure and in 3 there was also fluid distension of the stomach. Only one horse had known access to foreign material in the diet, but a further 3 were related to an exceptionally dry climate period. Five of the 6 horses recovered following surgery.

The value of arterial blood pressure measurement in assessing the prognosis in equine colic.

Indirect arterial blood pressure was determined on 33 horses prior to surgical intervention for the diagnosis and/or correction of acute abdominal disorders and a relationship between low systolic blood pressure and non-survival was established. It is suggested that blood pressure determination should be used to augment other methods of clinical and laboratory examination in cases of equine colic.

Collateral arterial blood supply to the normal and ischemic canine kidney.

Latex rubber was perfused into the abdominal aorta of 10 healthy dogs. Each kidney was found to have 4 to 6 vascular extensions of interlobar or arcuate arteries which communicated with an extrarenal artery. Renal collateral arterial connections were made with the phrenicoabdominal, spermatic, deep circumflex iliac, ureteral, caudal mesenteric, lumbar, and adrenal arteries. The renal collateral circulation was stimulated in 4 dogs by gradual compression of the renal artery and the presence of hypertrophied vessels confirmed by angiography. In 1 of these 4 dogs, the right renal artery was gradually compressed and finally occluded. Subsequently, contralateral nephrectomy was performed. Nine weeks later, the dog was still active, alert, and eating well.

The management of rectal tears in horses.

Rectal trauma in horses is usually iatrogenic and carries a high mortality. Partial thickness tears heal without surgical assistance. Full thickness tears require surgical repair through the anus or a ventral laparotomy or, if these are not possible because of difficulty in gaining access to the tear in its usual site at the pelvic inlet, a diverting colostomy to allow the rectum to heal is necessary. This paper describes the management of 15 cases of rectal injury, only 3 of which survived. Two of these were partial thickness tears not treated surgically and the third had a temporary diverting colostomy.

An oesophageal diverticulum in a dog.

An 11-month-old male Miniature Poodle was found to regurgitate small volumes of fluid and food particles due to a diverticulum in the thoracic oesophagus. The diverticulum was removed surgically. Histologically the wall contained extensive scar tissue. Longterm recovery was uneventful and 5 months after surgery the dog is in good health

Obstruction of the small colon by intramural haematoma in three horses.

Three cases of intramural haematoma of the small colon of horses are presented. In all cases the haematoma obstructed the lumen and caused an accumulation of faeces and gas. The horses were in shock and had acute abdominal pain. Exploratory abdominal surgery revealed the haematomas and showed them to be associated with chronic infection and terminal rupture in one animal which was subsequently killed, and an iatrogenic perforation of the terminal small colon in another which survived after intestinal resection. In the remaining horse, which died without recovering after intestinal resection, no cause was found.

Fieldwork experience, Part I: Impact on practice preference.

Occupational therapy students and student supervisors in 65 fieldwork centers nationwide responded to a survey designed a) to appraise the relative value of the fieldwork experience in the occupational therapist's professional development and b) to identify the elements perceived as being essential to a good fieldwork experience. Three stages of professional development were examined: the preprofessional, the academic, and the fieldwork experience. Results suggest that the fieldwork experience stage has the greatest impact on the development of a therapist's preference for a specific area of clinical practice. This article discusses the primary influences in the three stages that contribute to this preference formation.

Fieldwork experience, Part II: The supervisor's dilemma.

This paper examines the distinguishing characteristics of the effective and the ineffective supervisor and the role, responsibilities, problems, and current needs of the occupational therapy student supervisor. Data were obtained through questionnaires received from 188 therapists and 127 students in 65 fieldwork centers nationwide. Responses indicate a perceived lack of adequate preparation of occupational therapists for the role of student supervisor and provide evidence that the profession needs to assume a more active role in providing formal, standardized training programs for the occupational therapy student supervisor. The results demonstrate a need for greater accountability for the quality of the fieldwork experience and the supervisory process guiding that experience.

Workplace stress, mental health, and burnout of veterinarians in Australia.

OBJECTIVE: To determine the frequency of the states of depression, anxiety, stress and burnout using internationally validated methods and to relate these to the demographic characteristics of veterinarians in Australia. METHODS: A postal survey of registered veterinarians with at least one year's experience and whose address was available; 1947 returned the questionnaire providing data for analysis. RESULTS: Overall, veterinarians describe higher levels of depression, anxiety, stress and burnout than the general population. The severity of these states was determined by gender, background, type of practice and years after graduation. CONCLUSIONS: Modifying the curricula of veterinary schools to include the teaching of personal cognitive and coping skills to undergraduate veterinary students, the provision of the opportunity to enhance these skills throughout their veterinary career and changes in the veterinary workplace could result in improved mental health, increased job engagement and work satisfaction.