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Biomedical subjects

J C Baron

Publications and source records attributed to J C Baron.

At least 163 records · Page 9Linked to original sources
PubMed1990

Effects of capsular or thalamic stroke on metabolism in the cortex and cerebellum: a positron tomography study.

We used positron emission tomography to study the cortical and cerebellar metabolic rates in 21 strictly selected patients with pure internal capsular infarct (n = 8), thalamocapsular hemorrhage (n = 6), or pure thalamic stroke (n = 7). Significant diffuse ipsilateral cortical hypometabolism relative to 62 controls free of cerebrovascular risk factors was frequently, although not consistently, found in the 13 patients with thalamocapsular or thalamic lesions and neuropsychological impairment but was absent from the eight patients with pure internal capsule infarct and free of neuropsychological deficit. These data suggest that damage to the thalamus or the thalamocortical projections is important in the development of ipsilateral cortical hypometabolism and that the latter may underlie the associated neuropsychological impairment. Significant contralateral cerebellar hypometabolism relative to 49 controls was found in three of six patients with pure internal capsule infarct, suggesting a pathogenetic role for the corticopontocerebellar system. However, the occurrence of hypometabolism in two of six patients with thalamic lesions indicates that this phenomenon may also result either from damage to the ascending cerebellothalamocortical system or indirectly from hypofunction of the cerebral cortex. No systematic association was observed between crossed cerebellar hypometabolism and ipsilateral ataxia.

Analysis of Variance↗
PubMed1990

Striatal D2 dopaminergic receptors assessed with positron emission tomography and [76Br]bromospiperone in untreated schizophrenic patients.

Striatal D2 dopaminergic receptors of 12 drug-free schizophrenic patients and 12 normal subjects were investigated with positron emission tomography and [76Br]bromospiperone. Patients were classified according to DSM-III criteria, and their clinical symptoms were rated according to Andreasen's negative and positive symptom scales. The ratio of striatal to cerebellar radioactivity was taken as an index of striatal D2 dopamine receptor density. There was no significant difference between the control subjects and the overall schizophrenic group and no significant relationship between this index and the symptom ratings. However, state-dependent variables could partly account for the striatal D2 receptor density variability.

Adult↗
PubMed1990

[The value of ultrasound-guided multiple systematic biopsies in the early diagnosis of cancer of the prostate].

Endorectal ultrasonography using a 7 mHZ probe was performed in 99 patients with a negative history for surgery of the prostate and either findings on rectal examination suggestive of cancer (T3 stage excluded) or a serum level of prostate-specific antigen of 2.5 mg/ml or more. A biopsy gun was used to harvest 1.5 centimetre long specimens. Ultrasound-guided biopsies were performed in peripheral hypoechogeneic areas; in addition, regardless of the result of the endorectal ultrasonography, routine multiple ultrasound-guided biopsies were performed in both lobes of the prostate (3 per lobe). Morbidity consisted in two cases of prostatitis (2%). Among the 99 patients, ultrasound guided biopsies found 16 carcinomas (16.1%), and routine multiple ultrasound-guided biopsies found 32 (32.3%) carcinomas. Four patients with normal results upon rectal examination and endorectal ultrasonography were found to have carcinoma of the prostate. These findings suggest that the morbidity of routine multiple ultrasound-guided biopsies is low; that routine multiple ultrasound-guided biopsies is more sensitive than ultrasound guided biopsies, with 16/99 (16%) additional carcinomas detected in this study and 56% of carcinomas among those patients with findings upon the rectal examination suggestive of malignant disease; and that routine multiple ultrasound-guided biopsies can allow the detection of carcinomas responsible for isolated elevation of prostate-specific antigen levels without anomalies of the rectal examination or endorectal ultrasonography (8% of the carcinomas in this study).

Antigens, Neoplasm↗
PubMed1990

[Urethral stricture in children. Long term results of surgical treatments].

Thirty-six urethral strictures were treated between 1977 and 1984. Three strictures were considered to be congenital, eleven were traumatic and twenty-two were iatrogenic. The authors performed twenty five internal urethrotomies, twelve resection-sutures of the urethra and eleven urethroplasties including eight patch grafts with a pedicle derived from scrotal or penile skin, a tubed pedicle scrotal skin flap, one Jurascek urethroplasty and one Leveuf urethroplasty. Internal urethrotomy only gave 50% of good results and is now reserved for short strictures less than one centimetre in length. Resection-suture is an excellent operation which should be reserved for strictures less than two centimetres in length: it gave 84% of good results. One of the various types of pedicle cutaneous urethroplasty is certainly the best operation for long strictures: it gave more than 90% of good results in the present series.

Adolescent↗
PubMed1990

[Ambulatory urologic surgery].

Since November 1st, 1988, an outpatient clinic has been set up in our department of Urology. Patients come to the clinic on the morning of the procedure and leave in the evening after a few hours of monitoring. Eligibility for outpatient surgery is determined using strict social, surgical and medical criteria. A visit with the anesthesiologist is scheduled one week before the operation. On the day of the procedure, the patient arrives at 7 a.m., is shaved, prepared and operated on by a senior surgeon before impatient operations begin. Postoperative monitoring is carried out as usual and around 6 p.m. the surgeon and the anesthesiologist decide whether the patient can be discharged. Most patients are interviewed by telephone within one week of the procedure. From November 1988 through December 1989, 172 adults were admitted to the outpatient clinic for endoscopic surgery (85 cases), open surgery (42 cases) or other procedures including diagnostic investigations, instillations, and removal or replacement of stents (44 cases). Twenty-three patients were discharged only on the day following the procedure. One patient was readmitted for clotting in the bladder. These preliminary results show that, as compared to inpatient surgery, outpatient surgery is cost-saving, easier to cope with psychologically and less apt to be followed by nosocomial infection, without greater risk to the patient provided inclusion criteria are stringently applied.

Adolescent↗
PubMed1990

[Stenosis of the urethra in children. Long-term results of surgical treatment].

Thirty-six urethral strictures were treated between 1977 and 1984. Three strictures were considered to be congenital, eleven were traumatic and twenty-two were iatrogenic. The authors performed twenty five internal urethrotomies, twelve resection-sutures of the urethra and eleven urethroplasties including eight patch grafts with a pedicle derived from scrotal or penile skin, a tubed pedicle scrotal skin flap, one Jurascek urethroplasty and one Leveuf urethroplasty. Internal urethrotomy only gave 50% good results and is now reserved for short strictures less than one centimetre. Of resection-suture is an excellent operation which should be reserved for strictures less than two centimetres: it gave 84% of good results. One of the various types of pedicle cutaneous urethroplasty is certainly the best operation to treat long strictures: it gave more than 90% of good results in the present series.

Adolescent↗
PubMed1990

[Infectious manifestations of AIDS in the urogenital tract].

Urogenital manifestations of AIDS appear today with an increasing incidence. Among 43 seropositive patients, seen in our department between 1985 and 1989, 19 were treated for an infection: 11 cases of epididymitis, 6 cases of prostatitis, 1 renal abscess, 1 case of extensive condylomata of the urethra. The clinical signs and follow up of these infections were straightforward in half of the cases. However, in some patients, the infection was fulminant with progression to an abscess despite the use of antibiotics or were unusual because of the pathogens isolated. Any urologist is likely to encounter cases of genitourinary complications of AIDS and should develop general measures of protection of the surgical team.

Abscess↗
PubMed1989

Striatal dopamine receptor occupancy during and following withdrawal from neuroleptic treatment: correlative evaluation by positron emission tomography and plasma prolactin levels.

The percentage occupation of striatal dopamine D2 receptors has been evaluated in 25 patients using 76Br-bromospiperone positron emission tomography (PET) and prolactin plasma levels (PRL) during oral neuroleptic treatment (11 studies), 1-90 days following discontinuation of such treatment (16 studies), and 1-120 days after last intramuscular administration of depot neuroleptics (nine studies). The PET-estimated occupation was highly significantly correlated in a sigmoid-like fashion to the logarithm of the chlorpromazine-equivalent dose of oral neuroleptics (suggesting a strict dose-occupation relationship during oral neuroleptic treatment and supporting the D2-mediated hypothesis of neuroleptic action), while PRL was weakly related to daily dosage. Following withdrawal, return to normal receptor availability, as estimated by PET, occurred within 5-15 days (suggesting that protracted effects of neuroleptics after withdrawal are not due to sustained D2 receptor occupation), but PRL values fell even more rapidly. Efficient treatment with depot neuroleptics resulted in marked PET-estimated D2 receptor occupation, stable over the whole 4-week drug-administration interval, suggesting that longer intervals could be appropriate; PRL values bore no relationship to PET-estimated occupation, indicating variable intersubject tolerance to neuro-endocrine dopamine blockade. Overall, PET was much more sensitive than PRL to estimate striatal D2 receptor occupation in vivo.

Adult↗
PubMed1989

Time course of effects of unilateral lesions of the nucleus basalis of Meynert on glucose utilization by the cerebral cortex. Positron tomography in baboons.

In order to investigate the effects of a partial cholinergic deafferentation on the functional activity of the cortex, the cerebral metabolic rate of glucose (CMRGlu) was measured with positron emission tomography and 18F-2-fluoro-2-deoxy-D-glucose in 5 baboons (Papio anubis) both before and serially following stereotaxic electrocoagulation of the left nucleus basalis of Meynert (NbM). Four days postlesion, significant metabolic depression was present in the entire ipsilateral cerebral cortex, most marked in the frontotemporal region, and which slowly recovered close to normal within 6-13 weeks. Postmortem studies showed that the lesions were located largely in the NbM, and that a significant decrease in choline-acetyltransferase (ChAT) activity was present in the ipsilateral frontal, temporal and parietal cortices. The animal with the most limited histological lesion showed the least decrease in both ChAT activity and CMRGlu. There was a highly significant linear correlation between the regional cortical decreases in CMRGlu (early postlesion data) and in ChAT activity. These results indicate that cholinergic deafferentation induces a proportional metabolic depression in the cortex. However, compensatory mechanisms operate to restore the cortical metabolic activity gradually despite sustained cholinergic denervation, pointing to pre- and/or postsynaptic adaptation (plasticity). Moreover, unilateral NbM lesions also induced a significant reduction in contralateral CMRGlu, which also demonstrated recovery. Several mechanisms are discussed to explain this contralateral effect, but the most likely implicates a transcallosal depression of function as a result of ipsilateral effects of the NbM lesion. These metabolic effects of cholinergic deafferentation in the primate provide new insight into the mechanisms of cortical dysfunction, and the recovery thereof, following subcortical lesions. In addition, our findings have some relevance to the cortical consequences of cholinergic deafferentation observed in dementia of Alzheimer type.

Animals↗
PubMed1989

Obsessive-compulsive and other behavioural changes with bilateral basal ganglia lesions. A neuropsychological, magnetic resonance imaging and positron tomography study.

Eight patients are reported who shared the combination of bilateral basal ganglia lesions and a frontal lobe-like syndrome. The main features were inertia and loss of drive, with preservation of intellectual function. Some patients showed stereotyped activities with compulsive and obsessive behaviour which were sometimes highly elaborate in pattern. Extrapyramidal clinical signs were absent or mild. Brain damage, related to anoxic or toxic encephalopathy, was demonstrated by CT scans and MRI. The lesions appeared to be confined to the lentiform nuclei, particularly affecting the pallidum, although there was generalized brain atrophy in 2 cases. Positron emission tomography (PET) in 7 patients revealed hypometabolism of the prefrontal cortex relative to other parts of the brain. The PET studies suggest dysfunction of the prefrontal cortex as a result of damage to the lentiform nuclei. These clinical, anatomical and functional observations emphasize the role of the circuits linking the prefrontal associative cortex and some specific areas of the neostriatum, including the pallidum. The existence of distinct nonoverlapping circuits in the motor field or in the associative field can explain the fact that basal ganglia lesions may give rise to a clinical picture that is either purely motor, purely behavioural (as in some of our patients), or both. Similarities existed between some symptoms found in our patients and certain features of major psychiatric illnesses such as severe depression, catatonic schizophrenia, and obsessive-compulsive disorder. This raises the hypothesis that some aspects of these psychiatric disorders could be related to structural and physiological disturbances in the systems linking the frontal associative cortex and the basal ganglia.

Adult↗
PubMed1989

Local brain haemodynamics and oxygen metabolism in cerebrovascular disease. Positron emission tomography.

Using position emission tomography (PET) and equilibrium imaging with oxygen-15 labelled gases, the cerebral blood flow (CBF), blood volume (CBV), oxygen extraction fraction (OEF) and oxygen consumption rate (CMRO2) were measured in multiple regions of interest over the cerebral cortex of 5 control subjects, 4 patients with strictly unilateral longstanding carotid artery occlusion, 1 patient with middle cerebral artery embolic stroke in the acute stage, and 4 patients with subcortical stroke and no cervical arterial disease. In each control subject, the regional CBV was linearly and positively correlated with both CBF and CMRO2, while the local mean transit time (t = CBV/CBF) was uniformly distributed, reflecting the local adaptation of both the vascular tone and the capillary density to the metabolic demand at constant cerebral perfusion pressure that characterizes the normal brain. In patients with subcortical stroke, cortical blood volume was reduced in proportion to the matched reduction in CBF and CMRO2, suggesting that the metabolic depression resulting from cortical deafferentation increases the resting tone of pial vessels. Unilateral carotid occlusion induced larger CBV and t, and steeper slopes of the CBV-CBF relationship, particularly on the occluded but also on the patent side. The assessment of the local cerebral perfusion pressure (CPP) as judged by the ratio CBF/CBV in 3 patients with focally raised OEF and preserved or reduced CMRO2, allowed the demonstration in multiple cerebral regions of single patients of two well-known physiological phenomena: the autoregulation of CBF, followed by the rise of the OEF as local CPP falls further. In addition, the depression of CMRO2 in the ischaemic cortex was associated with a trend for CBV to return towards normal values, compared with the maximally elevated CBV found in oligaemic but metabolically normal areas. This suggests that a process of metabolic vasoconstriction may participate, among other factors, in the vascular collapse that occurs, and would serve to regenerate some haemodynamic reserve, at very low CPP levels.

Arterial Occlusive Diseases↗
PubMed1989

Striatal dopamine D2 receptors in tardive dyskinesia: PET study.

The dopamine D2 receptors were investigated in vivo in eight neuroleptic-free patients with persistent tardive dyskinesia using positron emission tomography and 76Br-bromospiperone. The striatal receptor density, estimated by the striatum/cerebellum radioligand concentration ratio, was not elevated in patients as compared with age-matched controls but was positively correlated with the severity of orofacial dyskinesia assessed with the Abnormal Involuntary Movement Rating Scale. These results indicate that tardive dyskinesia is associated with normal levels of striatal D2 receptors but the severity of orofacial movements may depend on the relative density of striatal D2 receptors.

Aged↗
PubMed1989

Management of the urethra in patients undergoing radical cystectomy for bladder carcinoma.

Urethral carcinoma recurrence after radical cystectomy for bladder carcinoma is a rare but devastating condition. Among 140 male patients submitted to radical cystectomy, urethral carcinoma recurrence occurred in 11. Nine of whom died. Nine other patients underwent urethrectomy at the time of cystectomy or shortly afterwards. Five are alive with no evidence of disease, 4 died of local recurrence or distant metastasis. Prophylactic urethrectomy should be performed in the presence of carcinoma in situ in the prostatic urethra or involvement of the prostatic urethra from the bladder tumor. These criteria should be considered as an absolute contraindication for substitution enteroplasty.

Aged↗