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Biomedical subjects

B Hamel

Publications and source records attributed to B Hamel.

47 records · Page 3Linked to original sources
PubMed1979

Quantitative indices of clinical uremia.

The disabling, dialysis-responsive symptoms of clinical uremia primarily represent impaired functions of the nervous system. Accordingly, these studies used several quantitative electrophysiologic and cognition-dependent probes of nervous system function: peripheral nerve-conduction velocity, response latency and amplitude; electroencephalographic (EEG) power-spectrum analysis; visual evoked response latency; EEG responses to photic driving; and measures of integrated behavioral performance that stressed sustained and selective attention, reaction time, speed of decision-making, short-term memory, and mental manipulation of symbols. Probes of quanitified central nervous system function consistently revealed impairments that varied directly with the degree of renal failure, that improved following onset of maintenance dialysis, and that improved still further after successful renal transplantation. In contrast, measures of peripheral nerve function were generally unchanged. Neurobehavioral measures that are relevant to uremic symptomatology provide quantitative estimates of the clinically significant, whole-organism biologic effects of renal failure and its several treatments. Applications of such measures in studies of symptomatic states other than uremia are indicated also.

Adolescent↗
PubMed1978

Visually evoked cortical potentials in renal failure: transient potentials.

Transient visually evoked cortical potentials (VECPs) were recorded from patients with renal disease. Changes in VECP latencies are described for undialyzed patients, patients receiving dialysis therapy, and patients who received kidney transplants. Characteristics of VECP latencies in these patient groups as well as examples of changes in latency values with respect to time for two individual patients are examined. The basic overall finding is that the VECP latencies increase as a patient's clinical condition deteriorates and normalize as the condition improves.

Adolescent↗
PubMed1978

Quantitative assessment of photic driving in renal failure.

Photically driven EEGs were recorded from patients with renal disease using photic stimulation at integer rates between 3 and 12 flashes/sec. Changes in the structure of the power spectrum of the potentials produced by this stimulus paradigm are described as a function of a patient's clinical state. The basic overall findings are that (1) harmonic activity is attenuated while activity below the fundamental driving frequency is increased as a patient's clinical condition deteriorates, and (2) that these effects are substantially reversed and controlled by means of dialysis and renal transplantation.

Adolescent↗
PubMed1975

Neurotoxicity in uremia.

The dialysis patient is aware that his behavior evokes reciprocal and complicating responses from important people in his environment. These interactions are perceived and conducted by neurochemical mechanisms which may be impaired in the abnormal chemical environment imposed in renal failure. It is the behaviors we comprehend as indicators of disordered nervous mechanisms. Therefore, it is logical that neurophysiological and neurobehavioral phenomena should be measured quantitatively in order 1) to estimate objectively the patients' success in achieving the goal of maintenance dialysis treatment, 2) to assess the comparative adequacy of dialysis regimens and 3) to provide objective endpoint measures which are relevant to uremia for further investigations of the etiology and pathogenesis of these critically significant uremic manifestations. Our experimental results illustrate that: 1) measures of conduction velocity, distal latency and response amplitudes, as employed by us, were relatively insensitive in the patients and circumstances studied; 2) several neurophysiological measures, i.e., the spontaneous EEG, VER latency and, perhaps, photic stimulation, on the other hand, are highly correlated with the severity of renal failure; 3) behavioral measures of sustained attention and alertness (TMT), of short-term memory (ASTM) and of cognitive manipulation of symbols (AR) are also highly correlated with the severity of renal failure; 4) some measured abnormalities improve following dialysis, but not always to normal--three residual impairments may indicate dialysis in adequacy; 5) several of these measures can provide objective evidence for adequacy of dialysis and other clinical and treatment effects in patients with renal failure.

Auditory Cortex↗
PubMedDate not supplied

Parental origin of the fra(X) gene is a major determinant of the cytogenetic expression and the CGG repeat length in female carriers.

The fragile X [fra(X)] syndrome is the most frequent form of inherited mental retardation, and co-segregates with a fragile site at Xq27.3 as well as with insertion of a variable number of trinucleotide repeats in the 5'-end of the FMR-1 gene. As the fra(X) gene is transmitted by females as well as males, we have investigated whether the parental origin of the fra(X) gene has an effect upon the cytogenetic expression and CGG repeat length. An increased fragment length of 0.2-0.6 kb appeared to be associated with a very low expression or even complete absence of the fragile site as well as with a normal phenotype, and was seen mostly in cases of paternal inheritance. However, in most female carriers with the maternally inherited fra(X) gene we found dispersed fragments ranging from 1.4-6.5 kb or even complete absence of a hybridization signal. Within the group of female carriers with the maternally inherited fra(X) gene we found a statistically significant correlation between the level of the cytogenetic expression and the PstI restriction fragment length encompassing the CGG repeat. These data can be taken as indirect evidence that CGG repeat length and cytogenetic expression are causally related.

Cytogenetics↗
PubMedDate not supplied

High prevalence of the fra(X) syndrome cannot be explained by a high mutation rate.

The overall prevalence of the fragile X [fra(X)] mutation, as determined by population studies, is approximately 1 in 850 [Gustavson et al., 1986; Webb et al., 1986]. This prevalence suggests a very high mutation rate which, in turn, suggests that many patients have to represent sporadic cases. In order to obtain an accurate estimate of the proportion of sporadic cases, we performed genealogic, cytogenetic and DNA linkage studies as well as direct analysis of the CGG repeat in relatives of 84 fra(X) probands. We did not find any evidence for the presence of sporadic cases. In 11 probands consanguinity could be proven by the detection of common ancestors, in 5 related families up to 9 generations ago. In the other 6 related families the mutation could be traced back 4-6 generations. In 3 or more generation families we were able to demonstrate that half of the probands carried the grandpaternal fra(X) gene. These results imply that rather than a high mutation rate, both Normal Transmitting Males (NTM's) and mentally normal female carriers contribute considerably to the high prevalence of the fra(X) syndrome.

Female↗
PubMedDate not supplied

Dysmorphology and mental retardation: molecular cytogenetic studies in dysmorphic mentally retarded patients.

In an institutionalised population of 471 mentally retarded adult residents (436 males and 35 females), 18 patients (16 males and 2 females) with dysmorphic features were selected to perform FISH studies by using subtelomeric probes to discover cryptic terminal deletions or duplications, undetectable with standard banding techniques. In the 13 investigated patients, no abnormalities were found with a selected battery of subtelomeric probes. The results of cryptic chromosomal rearrangement studies are variable but the frequency of positive diagnostic findings seems to be lower than previously expected.

Adolescent↗
PubMedDate not supplied

A data base management system for clinical records of renal failure.

This paper describes a computerized data-base management system (DBMS) for keeping medical records of kidney failure patients. The system allows simple data entry by untrained medical personnel as well as automatic feeding of data from computer generated data files. The system allows easy retrieval which is enhanced by graphic displays and statistical analyses of the data. The DBMS uses a relational model of data representation and is based on an existing system which was developed to run under the UNIX operating system on DEC PDP 11's. Previous attempts by the authors and others to create such a medical record system are described. A description of the hardware and software environment of the medical record system is provided. The system is then described, and examples of data manipulations are given.

Computers↗
PubMedDate not supplied

[Clinical impact of atypical antipsychotics: prospective 6-month study of inpatients treated with risperidone or olanzapine].

A survey of clinical and therapeutic evolution in patients treated with an atypical antipsychotic, risperidone or olanzapine, was carried out at La Colombière Psychiatric Hospital, Montpellier. This prospective observational study was conducted over 6 months. Forty-nine patients were included in the olanzapine treatment group and thirty-five in the risperidone treatment group. The Clinical Global Impression (CGI) scale was used for evaluation at day 0, 7, 30, 90 and 180 of treatment. The majority of patients were improved after 30 days of treatment, and clinical improvement was observed in about 60 per cent of patients among those treated at day 180. The main therapeutic benefit occurred in respect of positive psychotic symptoms. Patients were discharged after 30 days of treatment. The atypical antipsychotic was not used with an additional neuroleptic for all patients. Tolerance was good, particularly for olanzapine. On the other hand, according to our results, others studies have to be performed to confirm the impact of the treatment on weight gain, assessment of subjective elements such as sedation, and the direct effect of the atypical antipsychotics on primary negative symptoms.

Adolescent↗
PubMedDate not supplied

[Mycobacterium avium complex infections: the point on the treatments].

Mycobacterium avium complex (MAC) infections are the most frequent opportunistic infections in AIDS. Since progress in antiretroviral drugs enables AIDS patients to survive longer, these infections involve an increasing number of sick people. Few controlled assays have evaluated the efficiency of several antibiotics. When used in monotherapy, clarithromycin (one gram twice a day) appeared as the most efficient drug while the effectiveness of azithromycin, clofazimine, rifampin and liposomal encapsulated gentamicin have not been truly proved. Due to its bacteriologic and clinical effects, the most interesting polytherapeutic scheme is the association of clarithromycin (1 g twice a day), ethambutol (15 mg per kg and per day) and rifabutin (600 mg per day).

AIDS-Related Opportunistic Infections↗