Use of anti-HBc positive allografts in adult liver transplantation: toward a safer way to expand the donor pool

The use of livers from anti-hepatitis B core (HBc) positive donors can alleviate donor shortage. Nineteen of 367 (6%) adults receiving anti-HBc positive allografts [three were hepatitis B antigen (HBsAg) negative, hepatitis B antibody (HBsAb) positive; four were HBsAg positive and 12 were not exposed to hepatitis B viral (HBV) infection] were retrospectively reviewed. In HBsAg negative recipients, immunoprophylaxis (IP) was guided by viral serology and immunohistochemistry (IH) of day 0 and day 7 liver biopsies. If IH was negative, IP was stopped. None of three HBsAg negative, HBsAb positive recipients infected; one (replicating) of four HBsAg positive recipients reinfected and seven of eight (87.5%) HBsAg, HBsAb negative recipients, who did not receive long-term IP, infected after a median time of 2 years (range 1-5); one patient died of liver failure. Four HBsAg, HBsAb negative recipients, receiving life-long IP, remained infection free. Anti-HBc positive donor livers must be directed selectively first to HBsAg positive recipients, next to recipients having HBV antibodies and finally to HBV-naive recipients. Identification of both donor and recipient risk factors for HBV infection before transplantation allows indiscriminate use of antiviral prophylaxis. The necessity for IP therapy should be guided by HBV-DNA testing of donor liver tissue and serum. IH of early liver biopsies is an unreliable marker for predicting antiviral treatment requirements.     

Evaluation of 2,3,5-triphenyltetrazolium chloride staining to delineate rat brain infarcts.

BACKGROUND AND PURPOSE: Accurate and reproducible determination of the size and location of cerebral infarcts is critical for the evaluation of experimental focal cerebral ischemia. The purpose of this study was to compare intracardiac perfusion of 2,3,5-triphenyltetrazolium chloride with immersion of brain tissue in 2,3,5-triphenyltetrazolium chloride to delineate brain infarcts in rats. METHODS: After 6, 24, or 48 hours of ischemia induced by permanent middle cerebral artery occlusion, some rats were perfused with 2,3,5-triphenyltetrazolium chloride; other rats were given an overdose of barbiturates, after which brain sections were immersed in 2,3,5-triphenyltetrazolium chloride. Coronal sections were taken 4, 6, and 8 mm from the frontal pole, and infarct areas in perfused and immersed sections were compared; subsequently, the same sections were stained with hematoxylin and eosin. RESULTS: In rats subjected to 24 or 48 hours of occlusion, areas of infarction were clearly defined with both 2,3,5-triphenyltetrazolium chloride staining techniques, and the infarct sizes correlated well with the results of hematoxylin and eosin staining (r = 0.85-0.94). CONCLUSIONS: These results demonstrate that intracardiac perfusion of 2,3,5-triphenyltetrazolium chloride is an accurate, inexpensive, and efficient staining method to detect infarcted tissue 24 and 48 hours after the onset of ischemia in rats.     

Sparing of perceptual implicit memory despite suppression of the electrophysiological word repetition effect: a study with general anesthetic isoflurane.

OBJECTIVE: Much effort has been devoted to the search for the neurophysiological correlates of implicit memory. A commonly held view is that the early portion (250-500 ms) of the event-related potential (ERP) word repetition effect reflects processes important for perceptual implicit memory whereas the latter portion reflects processes implicated in explicit memory. It is, however, difficult to disentangle with certainty the relative contributions of each form of memory on ERPs since both forms co-exist in normal subjects. To dissociate ERP effect related to implicit and explicit memory, we used isoflurane sedation in normal subjects to suppress explicit remembering while sparing implicit memory. These ERPs were compared with those of non-medicated control subjects. METHODS: Thirteen subjects performed an incidental encoding task for words presented auditorily during the inhalation of a subanesthetic dose of isoflurane. After termination of isoflurane administration, we assessed free recall and recorded ERPs during a syllable completion task (implicit memory) and during a passive listening task (ERP repetition effect). Eleven non-medicated control subjects were tested in a similar manner. RESULTS: The controls showed robust early and late ERP repetition effect. The isoflurane group had implicit memory without free recall and showed no ERP repetition effect. CONCLUSIONS: These findings failed to show an association between any part of the repetition effect and perceptual implicit memory. The results are consistent with the view that processes linked to explicit memory contribute to the ERP repetition effect since there was a marked difference in free recall between the control and isoflurane groups. SIGNIFICANCE: The present study shows that the reversible alterations of memory by general anesthetics can be used to study the neurophysiological correlates of memory processes.     

Intraoperative ultrasound imaging of the entire brain through unilateral exploratory burr holes after severe head injury: technical note

A portable ultrasound unit with a 3.5-MHz probe allows accurate imaging of both cerebral hemispheres and partial imaging of the posterior fossa through unilateral exploratory burr holes or a craniotomy. In patients with clinical signs of transtentorial herniation after severe head injury, this unilateral technique can detect extraaxial and intraparenchymal mass lesions more accurately than is possible with bilateral exploratory burr holes.     

Value of Doppler ultrasound for the diagnosis of renal artery stenosis in children

To evaluate the reliability of Doppler ultrasonography (US) in identifying children with renal artery stenosis (RAS) among those with hypertension, we compared Doppler US results in 22 hypertensive children (mean age 8.9±4.3 years), with (13 cases) and without RAS at angiography, and in 33 normotensive children (mean age 8.8±4.7 years). We observed 2 false-negatives and 2 false-positives with Doppler US. Of the 2 false-negative diagnoses, 1 had RAS on an accessory renal artery located behind a normal upper polar artery and the other was observed in a patient with bilateral multiple stenosis of the very distal segments of renal arteries. The 2 false-positive diagnoses were due to sinuous left renal artery and to technical reasons, respectively. In another patient, Doppler US showed a tight RAS, while arteriography was normal. RAS was subsequently confirmed by a second arteriography. Peak systolic velocity values of Doppler US were significantly higher in patients with proven angiographic RAS (3.44±0.66 m/s) than in hypertensive patients with normal renal arteries at angiography (0.99±0.35 m/s, P <0.0001) and normotensive healthy children (1.04±0.23 m/s, P <0.0001). With the use of multiple views, and the experience acquired with practice, false-negatives or false-positives due to the geometry of the renal artery can be avoided. Nevertheless, very distal stenosis can be missed by Doppler US. Received October 30, 1995; received in revised form April 16, 1996; accepted May 14, 1996     

Some of the factors to be considered in the prescription and timing of bitewing radiography in the diagnosis and management of dental caries.

This article describes some of the factors to be considered by the practitioner when prescribing bitewing radiographs in the diagnosis and management of dental caries and draws on the literature of a number of disciplines including restorative dentistry, cariology, epidemiology and oral radiology. It seems appropriate to re-assess current practice in the light of information on changes in the disease of dental caries, its behaviour and the way this behaviour may vary in high and low caries risk groups. The diagnostic potential of the bitewing examination appears, at present, to be unrivalled, but other diagnostic methods, such as fibreoptic transillumination and tooth separation, must also be considered. Some methods to minimize radiation doses and increase diagnostic yield are discussed. Current knowledge of prescribing patterns is reviewed and areas of ignorance are mentioned as findings from future research in these areas may influence decisions about when to use and re-use bitewing radiographs.     

Is computed tomographic scanning necessary in patients with tentorial herniation? Results of immediate surgical exploration without computed tomography in 100 patients

Computed tomographic (CT) scans are performed on virtually all patients with severe head injury at the time of admission. Because of the time involved in obtaining these studies, the evacuation of significant intracranial mass lesions is delayed. To avoid such delays, the authors performed burr-hole exploration for the diagnosis of intracranial hematomas before CT scans were obtained in 100 consecutive head-injured patients with clinical signs of tentorial herniation or upper brain stem dysfunction upon admission to the emergency room. Patients in whom a hematoma was discovered had a craniotomy for evacuation of the clot; those in whom the exploration was negative had a CT brain scan immediately after operation. Burr-hole exploration revealed extracerebral mass lesions in 56 patients. In 38 patients, the exploration was negative, and postoperative CT scanning showed no significant hematoma. Of 6 patients in whom the CT scan demonstrated extraaxial hematomas requiring surgical evacuation, 4 had subdural hematomas that were missed because the exploration was incomplete; 1 patient had an epidural hematoma and 1 had a subdural hematoma contralateral to a craniotomy on the side of a positive initial burr-hole exploration. Our results indicate that the relatively small subgroup of head-injured patients with early tentorial herniation or upper brain stem compression have a high incidence of immediate extraaxial hematomas and a low incidence of intracerebral hematomas. This is particularly true of patients over 30 years of age and those who suffer low speed trauma, such as falls and vehicle-pedestrian accidents.