Factor VIII-von Willebrand factor requires calcium for facilitation of platelet adherence

The role of divalent cations in platelet adherence to deendothelialized human arteries in flowing blood was investigated in an annular perfusion chamber. Spreading of platelets on the subendothelium was impaired below 30 microM of free Ca2+ ions (Ca2+). When Ca2+ was replaced by Mg2+, adherence was unchanged in perfusates without exogenous factor VIII-von Willebrand factor (FVIII-vWF), but the ability of FVIII-vWF to support platelet adherence was lost. Binding of FVIII-vWF to the vessel wall was independent of divalent cations, but bound FVIII-vWF was only able to mediate adherence after exposure to Ca2+. Pretreatment of FVIII-vWF with the calcium chelator EGTA (10 mM) resulted in loss of the ability to facilitate platelet adherence, while the ristocetin cofactor activity remained intact. Full restoration of the ability to mediate platelet adherence could only be obtained by prolonged dialysis against Ca2+ in the millimolar range. These data indicate that divalent cations have at least two separate roles to play in supporting platelet adherence: (1) platelet spreading on the subendothelium requires Ca2+ or Mg2+; (2) FVIII-vWF should be exposed to Ca2+ to obtain its optimal biologic activity in supporting platelet adherence.     

Interventional radiologic procedures in the renal transplant

Percutaneous interventional procedures can be valuable in the evaluation and treatment of urologic complications of renal transplantation. Thirty-three patients underwent percutaneous procedures, including relief of obstruction by catheter nephrostomy, diagnostic antegrade pyelography with Whitaker testing, aspiration of various fluid collections (lymphocele, hematoma, urinoma, and abscess), and renal artery angioplasty, during a three year period at three institutions, to provide temporizing treatment and anatomic data. Surgical intervention was sometimes avoided, but more often it could be deferred to allow the patient to stabilize prior to surgery. Complications that required surgery occurred in two patients.     

Carotid endarterectomy: a ten-year analysis of outcome and cost of treatment

Between 1978 and 1988, 215 patients with an average age of 67 years, underwent 246 carotid endarterectomies. Two hundred ten (85.4%) patients were symptomatic, and 36 (14.6%) were asymptomatic. Six patients (2.4%) had a postoperative stroke, and all had immediate reoperation. One of these patients died (30 day mortality rate, 0.4% for the series), and two (0.8%) recovered completely, whereas three (1.2%) had a mild permanent neurologic deficit. Two patients (0.8%) had nonfatal myocardial infarction. Mean follow-up of 42.2 months (range, 1 to 126 months) was achieved. At 5 and 8 years actuarial survival rates of 82% and 66% and stroke-free survival rates of 67% and 37% were observed. Actuarial stroke free rates of 90% at 5 and 8 years were noted. By introducing and observing guidelines that required preoperative study of most clearly defined classes of patients before admission for surgical treatment, the average length of stay for carotid endarterectomy was lowered from 9.5 days in the first 5 years of the study to 5.8 days in the second 5 years (p = 0.001). Average hospital charges, expressed in constant dollars, decreased from $3113 in the first 5 years to $2620 in the second 5 years (p = 0.02) despite an 88% inflationary increase in medical consumer price index. This experience shows that the length of hospitalization of patients with carotid endarterectomy can be reduced and the cost of admission lowered without untoward effect on perioperative morbidity and mortality rates.     

Neonatal subgaleal haematoma: Associated risk factors, complications and outcome

Objective : To describe the obstetric and perinatal factors, in particular the method of delivery, associated with development of a subgaleal haematoma (SGH) and to determine the outcome of survivors with this type of birth trauma. Methodology : Perinatal and obstetric data were retrospectively reviewed for 37 infants admitted to the neonatal unit of the sole tertiary paediatric referral hospital in Western Australia with an SGH, over a 24 year period from 1970 to 1993. These data were compared to data for all Western Australian births. The long-term outcome was obtained through medical and private paediatric records for 26 of these infants. Results : All except one of the neonates had instrumental deliveries; 89% had a vacuum extractor applied to the head at some stage of delivery compared to 10% of the general population of births in Western Australia. There was also a significantly increased risk of failure of attempted vacuum extraction. Of the cases where a vacuum extraction was attempted, 45% also had forceps applied to the head. Coagulopathy was associated with the severity of the SGH. There was also a high frequency of occurrence (40%) of associated head trauma such as intracranial haemorrhage, skull fracture and cerebral oedema, as well as neonatal encephalopathy (73%). The occurrence of these associated features did not correlate significantly with the severity of SGH. Minor complications of SGH included jaundice and facial bruising. There was an excess mortality associated with SGH; however, the long-term outcome for neonatal survivors with this disorder was good. None of the cases studied subsequently developed cerebral palsy or intellectual disability, and minor neurological sequelae only were documented in four infants. Conclusions : SGH is an uncommon type of birth trauma, and is associated with delivery or attempted delivery by vacuum extraction. The most commonly associated clinical problems were hypovolaemia and coagulopathy. The long-term outcome for neonates with this condition is good.     

Vagotomy plus Bilroth II gastrectomy for the prevention of recurrent alcohol-induced pancreatitis.

Three retrospective reviews documenting a lessened frequency of acute recurrent alcohol-induced pancreatitis following vagotomy, with or without gastrectomy or gastroenterostomy, prompted a prospective evaluation of truncal vagotomy with Bilroth II gastrectomy as a means of preventing such exacerbations. Randomization between operation and encouragement to abstain from alcohol in patients with a history of more than one, but less than ten, acute bouts of alcohol-induced pancreatitis was set by odd-even digits in the hospital number. Of 176 patients admitted with acute alcoholic pancreatitis during 23 months of study, 49 were excluded because of too few or too many prior attacks. Another 61 refused to enter the study. At least one (average 1.9) recurrence requiring hospitalization was noted in 49, or 80%, of these patients on follow-up for 2 to 26 months (average 14 months). Of the 66 who consented to participate, 33 were randomized not to undergo operation and had almost identical recurrence statistics (i.e., an average of 1.7 recurrences in 24, or 73%). By contrast, only two of 31, or six per cent, allocated to operation have experienced a recurrence (p less than 0.001). Two who had been randomized were excluded because of persisting active pancreatitis.     

Localized 1H NMR spectroscopy of rat spinal cord in Vivo

A movable, actively decoupled surface coil has been employed to obtain a localized ¹H NMR spectrum from the lumbosacral spinal cord of a live Lewis rat. A volume selective ‘VOSY’ normally spelled out as ‘volume selective spectroscopy’ spectroscopy pulse sequence that incorporates “phase ramped” selective RF pulses, has been used to minimize random phase jitter in the NMR signal as a result of the large frequency shifts required to locate the voxel in the center of the cord while using intense gradient pulses. Spectra from 13-μl voxels in healthy rats and in rats inoculated with guinea pig spinal cord and complete Freund's adjuvant, resulting in experimental autoimmune encephalomyelitis, are shown.