MR imaging of human brain at 3.0 T: preliminary report on transverse relaxation rates and relation to estimated iron content

PURPOSE: To determine the transverse relaxation rates R2 and R2' from several gray matter regions and from frontal cortical white matter in healthy human brains in vivo and to determine the relationship between relaxation rates and iron concentration [Fe]. MATERIALS AND METHODS: Six healthy adults aged 19-42 years underwent thin-section gradient-echo sampling of free induction decay and echo magnetic resonance (MR) imaging at 3.0 T. Imaging covered the mesencephalon and basal ganglia. RESULTS: Relaxation rates (mean +/- SD) were highest in globus pallidus (R2 = 25.8 seconds-1 +/- 1.1, R2' = 12.0 seconds-1 +/- 2.1) and lowest in prefrontal cortex (R2 = 14.4 seconds-1 +/- 1.8, R2' = 3.4 seconds-1 +/- 1.1). Frontal white matter measurements were as follows: R2 = 18.0 seconds-1 +/- 1.2 and R2' = 3.9 seconds-1 +/- 1.2. For gray matter, both R2 and R2' showed a strong correlation (r = 0.92, P < .001 and r = 0.90, P < .001, respectively) with [Fe]. Although the slopes of the regression lines for R2' versus [Fe] and for R2 versus [Fe] were similar, the iron-independent component of R2' (2.2 seconds-1 +/- 0.6), the value when [Fe] = 0, was much less than that of R2 (12.7 seconds-1 +/- 0.7). CONCLUSION: The small iron-independent component R2', as compared with that of R2, is consistent with the hypothesis that R2' has higher iron-related specificity.     

Laparoscopic-assisted continent urinary diversion in obese patients

BACKGROUND AND PURPOSE: The Pfannenstiel incision provides good access to the bladder and bladder neck for major reconstructive surgery in the thin patient, whereas a midline incision is often necessary to get adequate exposure in the obese patient. We describe our experience using laparoscopic-assisted continent urinary diversion in conjunction with other bladder and bladder neck surgery in obese patients. PATIENTS AND METHODS: Three female patients (mean age 18; mean weight 175 pounds) with neurogenic bladder underwent Mitrofanoff appendicovesicostomy continent urinary diversion to the umbilicus and pubovaginal sling. An umbilical port for the telescope and two lateral ports were used. Once the appendix and right hemicolon had been completely mobilized up to the hepatic flexure, reconstruction was completed through a low Pfannenstiel incision. RESULTS: There were no laparoscopic complications. None of the laparoscopic port sites was visible postoperatively, as one was in the base of the umbilicus, and the other two had been incorporated into the Pfannenstiel incision. With a mean follow-up of 1 year, all patients were continent and catheterizing their umbilicus easily. Pfannenstiel incisions were well healed, and the patients were quite satisfied with their cosmesis. CONCLUSION: Laparoscopic-assisted Mitrofanoff appendicovesicostomy continent urinary diversion to the umbilicus can be performed in conjunction with a Pfannenstiel incision to complete major bladder and bladder neck surgery in the obese patient with good postoperative cosmesis. This procedure represents a nice compromise between a very lengthy bladder reconstructive procedure done purely laparoscopically and a midline incision with good exposure but suboptimal cosmesis.     

Functional imaging of memory retrieval in deficit vs nondeficit schizophrenia

BACKGROUND: Neuroimaging studies have provided evidence of abnormal frontal and temporal lobe function in schizophrenia. Frontal cortex abnormalities have been associated with negative symptoms and temporal lobe abnormalities with positive symptoms. The deficit and nondeficit forms of schizophrenia were predicted to differ in prefrontal cortical activity, but not in medial temporal lobe activity. METHODS: Regional cerebral blood flow was studied using oxygen 15 positron emission tomography during 3 different memory retrieval conditions in 8 control subjects, 8 patients with the deficit syndrome, and 8 patients without the deficit syndrome. Behavioral and positron emission tomography data were analyzed using a mixed-effects model to test for population differences. RESULTS: In all memory conditions, frontal cortex activity was higher in patients without the deficit syndrome than in patients with the deficit syndrome. During the attempt to retrieve poorly encoded words, patients without the deficit syndrome recruited the left frontal cortex to a significantly greater degree than did patients with the deficit syndrome. The 2 schizophrenia subtypes did not differ in the activity or recruitment of the hippocampus during memory retrieval. CONCLUSION: Frontal cortex function during memory retrieval is differentially impaired in deficit and nondeficit schizophrenia, whereas hippocampal recruitment deficits are not significantly different between the 2 schizophrenia groups.     

Suicide in the course of the treatment of depression

Five different mechanisms have been proposed whereby antidepressant treatment might lead to suicide: first by simply ameliorating depressions more rapidly; second by an action intrinsic to the specific antidepressant effects; third by toxicity in overdose; fourth by side-effects of specific antidepressants; and finally by virtue of treatment inefficacy. Evidence from randomized control trials (RCT), controlled case studies and epidemiological studies on this question is reviewed and it is concluded that antidepressants can be implicated in some cases of suicide during treatment. Modifications of clinical trial methods and pharmacogenetic studies would yield a richer data set to explore this issue further.     

Interleukin-1 receptor antagonist in newborn babies and pregnant women

We have used patch-clamp techniques to study the effect of the sulfhydryl group oxidizing agents mercury and thimerosal on calcium-activated nonselective cation channels from brown adipose tissue. 100 nmol/l mercury and 50 mol/l thimerosal induced a complete block. Blockade could be reversed by reduction of the mercaptide by dithiotreitol (DTT). Mercury was found to be the most potent blocker (IC₅₀-value 21×10^–9 mol/l), whereas thimerosal (IC₅₀-value 1.5×10^–6 mol/l) was as effective as 3,5-dichlorodiphenylamine-2-carboxylic acid (DCDPC). The DCDPC effect, however, could not be reversed by DTT, indicating different blocking mechanisms. It is concluded that SH-groups are involved in gating of the calcium-activated nonselective channel.     

Plant nurseries: a reliable resource for plant identification?

Poison Centers frequently rely on the assistance of local plant nurseries to identify unknown plants involved in exposures. The reliability and accuracy of utilizing this method has never been studied; therefore, our objective was to evaluate this primary resource of plant identification. A study was done in which callers were instructed to take plant samples to a local nursery for visual identification. Once the patient was treated according to our normal protocol, the plant specimen was sent to a botanist for a second identification. The botanist provided his identification results through a blinded process. The collected data was gathered from 68 cases that completed the necessary study criteria. In 58% of the cases, plant nurseries were an unreliable source for plant identification. These incorrect identifications resulted in the "undertreatment" in 24% of the exposures.     

Primary cerebral lymphoma: a study of 47 cases probed for Epstein-Barr virus genome.

AIMS: To determine the prevalence of Epstein-Barr virus genome in primary cerebral lymphomas occurring in the absence of immune suppression. METHODS: Forty eight consecutive patients with lymphomas restricted to the central nervous system were identified, all of whom had had neurosurgical biopsies performed at the National Hospitals for Neurology and Neurosurgery, London. Only five patients had some form of underlying immune deficiency; 43 were apparently normal. The tumours were studied with immunohistochemical markers and by in situ hybridisation, using a biotinylated probe to the internal repeat region of Epstein-Barr virus. RESULTS: All the lymphomas were B cell in origin. Tumours from the five immunosuppressed patients all showed hybridisation, as did two of the "spontaneous" tumours. CONCLUSIONS: This is the largest series of cerebral lymphomas so far probed for Epstein-Barr virus genome: as more are examined, it is suggested that a small proportion of the tumours from immunocompetent patients will also contain the virus.     

Comparison of enhancement of GGTase-positive foci and induction of ornithine decarboxylase in rat liver by barbiturates

The induction of ornithine decarboxylase (ODC) by barbituratesand the ability of barbiturates to enhance neoplastic progressionof chemically initiated cancer was examined in rat liver. Allseven barbiturates induced ODC with barbital (7.7 fold increase)and phenobarbital (5.7 fold increase) demonstrating the mostpotent activity. Maximum induction of ODC by phenobarbital wasobtained in 18 h. Barbital (500–5000 p.p.m.) and phenobarbital(500 p.p.m.) administered in the drinking water enhanced theappearance of diethylnitrosamine (DENA)-initiated -glutamyltranspeptidase(GGTase)-positive foci. Amobarbital, hexabarbital and pentabarbitaldid not enhance the appearance of GGTase-positive foci. In theabsence of previous initiation by DENA, the enhancing regimenof the barbiturates did not cause the appearance of GGTase-positivefoci. Barbiturates induced ODC activity in rat liver and enhancedthe incidence of DENA initiated GGTase-positive foci.