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Biomedical subjects

M Gross

Publications and source records attributed to M Gross.

At least 433 records · Page 24Linked to original sources
PubMed1988

The effect of neuroleptics on dysfunction in a prefrontal substrate of sustained attention in schizophrenia.

Regional brain metabolism was measured in patients with schizophrenia during the performance of auditory discrimination to evaluate the effect of neuroleptic medication on the middle prefrontal cortex, an area that appears to be an important biological determinant of the sustained attention required of subjects in this task. While unmedicated patients with schizophrenia have lower than "normal" metabolic rates in this cortical area that are unrelated to performance, patients receiving neuroleptics appear to have this metabolic deficit attenuated with higher metabolism in this area associated with greater accuracy of performance. This change occurs in the context of differential neuroleptic effects on the cortical regions of the frontal cortex, increased metabolism in the basal ganglia, thalamus and temporal lobes, and no apparent effect in the parietal and occipital cortices. The findings suggest that only part of the abnormality in the prefrontal cortex determination of sustained attention in schizophrenia is sensitive to neuroleptic treatment.

Adult↗
PubMed1988

Therapy of rhabdomyosarcoma of the larynx.

A case of subglottic rhabdomyosarcoma in a 13-year-old boy is reported. Following partial conservative resection of the larynx with supplementary chemotherapy and without irradiation, the patient has had no functional impairment of the larynx and has shown no evidence of recurrence for more than 3 years.

Adolescent↗
PubMed1988

Wound healing following excimer laser radial keratotomy.

A pulsed excimer laser was used to produce radial keratotomy in vivo in human corneas and the wound healing process was studied. Fluences of 370 mJ/cm2 at a repetition rate of 20 Hz were effective and atraumatic. The wound healing process was remarkably uneventful without an inflammatory or immune reaction apparent at 21 days. Consistent flattening of the cornea was obtained by shallower cuts than with conventional radial keratotomy techniques.

Adult↗
PubMed1988

From syndrome to illness: delineating the pathophysiology of schizophrenia with PET.

The Section on Clinical Brain Imaging of the Laboratory of Cerebral Metabolism has been engaged in studying regional brain metabolism by positron emission tomography (PET) to establish the pathophysiology of schizophrenia. Recent studies have revealed that the fluorodeoxyglucose (FDG) PET methodology can be applied successfully to determine the anatomical substrata of directed attention. In normal controls, the metabolic rate in the middle prefrontal cortex, measured during the ongoing performance of auditory discrimination, is associated with their accuracy of performance. In unmedicated patients with schizophrenia, even those who performed as well as normals, the metabolic rate in the mid-prefrontal cortex was found to be significantly lower than normal. Further, this decreased metabolic rate was unrelated to performance. In medicated patients with schizophrenia, at least part of the metabolic deficit remains, but this deficit appears to be performance-related. These findings suggest several conclusions. The mid-prefrontal cortex and its dopamine neurotransmitter pathway input are important biological determinants of sustained attention. Two types of prefrontal metabolic deficits may contribute to dysfunctional goal-directed behavior and, more speculatively, vulnerability to psychosis in some patients with schizophrenia. One deficit is sensitive to neuroleptics, and thus presumably to a change in the balance of regional brain dopamine input. A second deficit is unaffected by neurolpetic treatment.

Brain↗
PubMed1988

High-dose naloxone in older normal subjects: implications for Alzheimer's disease.

The behavioral and cognitive effects of naloxone HCl, in doses of 5 micrograms/kg, 0.1 mg/kg, and 2.0 mg/kg administered as an IV bolus, were assessed in a double-blind, placebo-controlled, randomized study of eight normal subjects ranging in age from 44 to 74 years (mean 63). Naloxone produced mild behavioral effects with slight cognitive impairment after the 2.0 mg/kg dose only. The threshold, dose dependency, characteristics, and magnitude of these behavioral effects were similar to what has previously been reported in young normal subjects, but markedly different from those observed in patients with dementia of the Alzheimer type (DAT) matched in age to the current study sample. These data suggest that the metabolic fate of naloxone is not substantially affected by age within the range studied. The findings of this study provide further support for a role for endogenous opiate systems in the modulation of behavior and cognition, and suggest that the unusual behavioral sensitivity of patients with DAT to naloxone cannot be accounted for by the effect of age.

Adult↗
PubMed1988

Effect of carrier selection on immunogenicity of protein conjugate vaccines against Plasmodium falciparum circumsporozoites.

Conjugate vaccines against the sporozoite stage of Plasmodium falciparum were synthesized by covalently coupling the recombinant protein R32 [with the one-letter amino acid code of MDP-[(NANP)15NVDP]2LR] to tetanus toxoid, cholera toxin, choleragenoid, and Pseudomonas aeruginosa toxin A. Conjugates were produced by using adipic acid dihydrazide as a spacer molecule and carbodiimide as a coupling agent. The molar ratio of R32 to carrier protein ranged from 2.5:1 to 8.4:1. These conjugates were found to be stable, nontoxic, and nonpyrogenic. When adsorbed onto Al(OH)3, all conjugates were capable of inducing anti-R32 antibody. Conjugates made with either cholera toxin or Pseudomonas aeruginosa toxin A were significantly more immunogenic than those constructed with tetanus toxoid or choleragenoid. However, the magnitude of the immune response to the R32 moiety was not governed by the antibody response to the carrier protein.

Amino Acid Sequence↗
PubMed1988

Isolated tricuspid valve prolapse.

Tricuspid valve prolapse is commonly associated with mitral valve prolapse or other heart abnormalities and is rarely found as an isolated finding. A patient with isolated tricuspid valve prolapse is described which was discovered on routine examination of an asymptomatic pilot.

Adult↗
PubMed1988

[Procedures for on-line minimizing of eyelid and vertical eye movement artefacts in the EEG].

The analysis of electroencephalograms and event-related potentials may be difficult by the presence of eyelid and eye movement artifacts. In this paper a method is described, which allows a relatively simple on-line correction of vertical ocular activity, measurable by electro-oculogram, in several EEG channels. Eyelid and eye movement artifacts are being manifest in a different extension at a different EEG recording position. Using the electrooculogram, with the aid of a simple electronic device it is possible to differ between eyelid and eye movement artifacts, which will be corrected selectively. If only midline derivations are evaluated (Fz, Cz, Pz) the vertical EOG is sufficient and horizontal EOG may be left out from the correcting procedure. The efficiency of the procedure is proved by EEG and ERP records.

Electroencephalography↗
PubMed1988

A critique of the methodologies used in clinical studies of hip-joint arthroplasty published in the English-language orthopaedic literature.

In a search of the English-language orthopaedic literature that was published from 1960 through 1986, only four papers that reported on prospective studies of hip-joint arthroplasty were found. In the study presented here, the standard epidemiological methods that are applicable to the design and performance of prospective clinical trials in medicine were reviewed, and the identified papers were evaluated with respect to the use of these methods. In all four papers, grave deficiencies were identified. Finally, the effects of some controlled clinical trials in other surgical disciplines were briefly reviewed. On the basis of the findings in this study, it was concluded that adequate surgical trials should be completed before new procedures or new designs of prostheses, such as those used in hip-joint arthroplasty, are made available for general use.

Clinical Trials as Topic↗
PubMed1988

[Different forms of drug therapy for progressive sensorineural hearing loss in childhood].

Because of progressive sensorineural hearing loss 26 patients of the age of 2 to 19 years were treated for 10 days with infusions of prednisolone, pentoxifylline and piracetam. After this treatment improved, auditory thresholds were found in 58%. In comparison with a previous investigation (treatment with prednisolone and pentoxifylline except piacetam), no significant difference between these two methods of therapy was seen.

Adolescent↗
PubMed1988

Aircrew selection: a prospective study.

The medical reasons for rejection among 3,000 consecutive applicants for flight training were evaluated, and the effectiveness of the screening process determined by reviewing subsequent medical wastage occurring during flight training. Of the 46 cadets who left the course because of medical reasons, 8 withheld information which would have led to their rejection on the original screening examination (epilepsy 1, recurrent syncope 1, migraine headache 2, Crohn's disease 1, asthma 1, chronic knee pain 1, and chronic recurrent headaches 1). There were also two errors in medical processing. The other 36 cases could not have been predicted by current screening procedures. We conclude that the major deficiency in our screening process is the concealment or withholding of information by candidates for flight training.

Adult↗
PubMed1988

Iodine-125 cholesteryl iopanoate for measuring extent of atherosclerosis in rabbits.

Rabbits rendered atherosclerotic by mechanical aortic de-endothelialization and 6 wk of cholesterol feeding were administered estradiol-17 beta-cypionate, an anti-atherogenic agent in rabbits. These animals were compared to a similar, untreated group and control animals fed a regular non-atherogenic diet. Iodine-125 cholesteryl iopanoate ([125I]Cl), a nonhydrolyzable cholesteryl ester derivative, was administered intravenously at regular intervals throughout the study. Six days after the last dose of [125I]Cl, the animals were scanned with a gamma camera. After animals were killed, tissue distribution of the 125I radioactivity showed a significant decrease of [125I]CI accumulation in the aorta of estrogen-treated as compared to untreated, cholesterol-fed animals. However, the accumulation of [125I]CI in the aortas was insufficient to accurately define the presence of atheroma by gamma camera scintigraphy.

Animals↗
PubMed1988

Air accidents, pilot experience, and disease-related inflight sudden incapacitation.

The epidemiology of sudden death, the etiology of inflight sudden incapacitation, and the influence of pilot age and experience on air accident rates are reviewed in order to determine the aeromedical emphasis needed to minimize accidents. Sudden deaths in men over age 35 are nearly all due to coronary artery disease, whereas in those under 35 years they are mostly due to hypertrophic cardiomyopathy. The incidence of fatal accidents from human error is, however, far greater than that from physical illness. Since inexperienced pilots have a 2-3 times increased incidence of mishaps due to pilot error, the estimated risk of disease related in-flight sudden incapacitation should be balanced by consideration of pilot experience. Therefore, it may be preferable to grant waivers to experienced pilots with an increased incidence of disease-related inflight sudden incapacitation than to replace them with novices. We conclude that overly strict medical criteria may paradoxically increase accident rates.

Accidents, Aviation↗
PubMed1987

Dysfunction in a prefrontal substrate of sustained attention in schizophrenia.

Regional brain metabolism was measured in normal subjects and patients with schizophrenia while they performed an auditory discrimination task designed to emphasize sustained attention. A direct relationship was found in the normal subjects between metabolic rate in the middle prefrontal cortex and accuracy of performance. The metabolic rate in the middle prefrontal cortex of patients with schizophrenia, even those who performed as well as normals, was found to be significantly lower than normal and unrelated to performance. The findings point to a role of the mid-prefrontal region in sustained attention and to dysfunction of this region in schizophrenia.

Adult↗
PubMed1987

Evidence that phosphorylation of eIF-2(alpha) prevents the eIF-2B-mediated dissociation of eIF-2 X GDP from the 60 S subunit of complete initiation complexes.

Recent observations have indicated that eukaryotic initiation factor (eIF)-2 and GTP or GDP normally bind to 60 S ribosomal subunits in rabbit reticulocyte lysate and that when eIF-2 alpha is phosphorylated and polypeptide chain initiation is inhibited, eIF-2 X GDP accumulates on 60 S subunits due to impaired dissociation that is normally mediated by the reversing factor (eIF-2B). Current findings now indicate that inhibition due to phosphorylation of eIF-2 alpha is mediated, at least in part, by the inability to dissociate eIF-2 X GDP from the 60 S subunit of complete initiation complexes. At the onset of inhibition, there is an accumulation of Met-tRNA(f) and eIF-2 on the polysomes, despite a marked reduction in Met-tRNA(f) bound to 40 S subunits and Met-peptidyl-tRNA bound to the polysomes. This initial effect is not associated with the formation of "half-mers" (polysomes containing an extra unpaired 40 S subunit), and the 40 S X Met-tRNA(f) complexes, though reduced, still sediment at 43 S. When inhibition is maximal and the polysomes are largely disaggregated, there is an accumulation of 48 S complexes consisting of a 40 S subunit and Met-tRNA(f) bound to globin mRNA as well as small polysomal half-mers, such that residual protein synthesis occurs to about the same degree on "1 1/2"s and "2 1/2"s as on mono-, di-, and triribosomes. Exogenous eIF-2B increases protein synthesis on mono-, di-, and triribosomes and decreases that on half-mers. This is associated with reduced binding of Met-tRNA(f) and eIF-2 to ribosomal particles sedimenting at 80 S and greater and a shift from 48 S to 43 S complexes. These results suggest that eIF-2B must normally promote dissociation of eIF-2 X GDP from the 60 S subunit of complete initiation complexes before they can elongate but cannot when eIF-2 alpha is phosphorylated, resulting in the accumulation of these complexes, some of which dissociate into Met-tRNA(f) X 40 S X mRNA and 60 S X eIF-2 X GDP.

Animals↗