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Biomedical subjects

J Hewitt

Publications and source records attributed to J Hewitt.

At least 127 records · Page 7Linked to original sources
PubMed1979

[Knowledge of Solomon's epidermal nevus syndrome (author's transl)].

Solomon's epidermal nevus syndrome is a questionable entity, because of its clinical heterogeneity. Four cases are presented in this paper, with emphasis on the complex relationship between variable types of epidermal nevi and diverse kinds of associated nervous, ocular and bone abnormalities. Nevertheless, it is of practical interest to know the frequency and the variability of these ectodermal and mesodermal associated defects; whatever the epidermal nevus, a careful examination must be carried out, in search of ocular, nervous, bone and renal signs, and, less frequently, but more often than in other children, these patients seem to be exposed to visceral malignancies.

Adolescent↗
PubMed1978

Anxiety and classroom examination performance.

Studied classroom examination performance over the course of an entire semester as a function of (a) students' anxiety level (high, medium, low); (b) difficulty level of exam question (more vs. less difficult); (c) type of exam question (rote memory vs. generalization); (d) sex of S; and (e) intelligence level of S. As expected, there was a strong main effect of anxiety and a significant interaction between anxiety and item difficulty. The latter was consistent with the Hull-Spence formulation of learning and performance--as the habit strength of incorrect responses increases (i.e., as the items become more difficult), the superiority of low over high anxious Ss also should increase. When item difficulty was held constant, anxiety did not interact with type of exam question.

Achievement↗
PubMed1978

Structure analysis of small proteins by electron microscopy: valinomycin, bacitracin and low molecular weight cell growth stimulators.

Dark field electron microscopy was combined with optical filtering to study at high resolution the structure of the cyclopeptide antibiotics, bacitracin and valinomycin, and two proteins of unknown structure, LMW-CSA N and B, low molecular weight granulocyte colony stimulating activity isolated from medium conditioned with normal or leukemic leukocytes. For bacitracin and valinomycin the images faithfully represented the known structural features at a resolution of 0.5 nm or better, depicting a two-ring structure for bacitracin, as well as the position of the potassium ion in valinomycin. Both proteins of unknown structrue had at least one cyclic peptide portion. LMW-CSA N had a size of 2.0 nm, LMW-CSA B of 2.4 nm. A potential site of the calcium ionophoric activity in the latter protein was found to be in the larger of the two ring portions constituting the molecule.

Bacitracin↗
PubMed1978

[Menkes' disease (new skin and hair ultrastructural abnormalities) (author's transl)].

The authors report the sixth case of Menkes' kinky hair disease. This boy has been observed for as long as 16 months, and he his still alive at the time of publication. This genetic, X linked disorder of copper metabolism is always fatal in childhood. Diagnosis is evoked when is noted the conjunction of progressive cerebral degeneration, seizures, with pili torti and monilethrix. It can be asserted with the very low copper and cerulo-plasmin blood levels. Recognition of the disease in utero might be possible. New findings in skin' electron microscopy and hair' scanning electron microscopy are reported here. And two RX scanner of the brain have been performed.

Brain Diseases, Metabolic↗
PubMed1977

An investigation of mistranslation in vivo induced by streptomycin by an examination of the susceptibility of abnormal proteins to degradation.

Proteolysis rates in vivo were measured in Escherichia coli cultures during treatment with dihydrostreptomycin and under various other conditions. Dihydrostreptomycin treatment caused an increase in the proteolysis rate, compared to untreated controls. The proteolytic system in vivo responsible for the elevated proteolysis in the early stages of dihydrostreptomycin treatment, or that during canavanine and puromycin treatment, were not inhibited by addition of phenylmethanesulphonyl fluoride. This agent did inhibit proteolysis rates in cultures whose growth was inhibited by starvation, or had been completely stopped by dihydrostreptomycin. It seems, therefore, that the extremely high proteolysis rates in cultures at this stage of dihydrostreptomycin treatment were due to the action of two protease systems: the one concerned with the breakdown of abnormal proteins, and the other concerned with normal protein turnover and active during a non-specific decline of growth. The proteolytic rate at complete growth inhibition brought about by dihydrostreptomycin was intermediate between those induced by canavanine and puromycin at the same stage of treatment. This indicated a similar hierarchy in the extent and nature of abnormality in the proteins synthesized under these conditions. The relationship between the abnormality of proteins induced by dihydrostreptomycin and the importance of this in the antibiotic mechanism is discussed.

Bacterial Proteins↗
PubMed1977

Signal to noise enhancement in dark field electron micrographs of vasopressin: filtering of arrays of images in reciprocal space.

A technique for filtering arrays of images of dispersed molecules is presented which takes advantage of the crystallographic properties of regular arrays and the rapidity of optical treatment. A filter in reciprocal space consisting of perforations in a square or rectangular lattice, as determined by the image arrrangement, reduces noise and averages the images simultaneously by transmitting only regularly recurring image structure. The filter is universal for all image contents and introduces no additional biases. The signal to noise improvement approaches square root N for N independent images of the same molecule in the same configuration. The procedure which is simple, rapid and inexpensive, is demonstrated with the aid of dark field electron micrographs of the protein vasopressin and combined with iodination of that molecule to elucidate its structure.

Crystallography↗
PubMed1977

[Cutaneous manifestations of angio-immunoblastic lymphadenopathy].

The authors report four cases of angio-immunoblastic lymphadenopathy, presenting with cutaneous lesions: these have a tumoral presentation in two cases while in the other two, the polymorphic aspect of the cutaneous lesions is reminiscent of a toxidermic eruption. In contrast to the relative clinical polymorphism, the pathological findings are monomorphic, i.e., in all cases, there was a vascular proliferation together with a more or less dense cellular infiltrate consisting of cells indistinguishable from those involving the abnormal lymph nodes.

Female↗
PubMed1977

[Lymphomatoid granulomatosis: cyclic nodular lymphomatoid panniculitis with immunologic deficiency].

The case of a 66 years old woman having presented an unusual cyclic dermatosis of 11 months duration is reported. The cutaneous elements were successively located in a subcutaneous, dermal and epidermal situation, and presented a spontaneous healing with sometimes deep retractive residual scars after an ulceration or not. Pathologically, the lesions consisted in dense mononuclear infiltrates and vascular lesions. This disease was associated with an immuno-deficiency state characterized by extremely low levels of circulating IgM. This deficit was found to be persistant as it was still present two years later. However during this lapse of observation no cutaneous lesions recurred. The possible connexions of such a case with those of lymphomatous granulomatosis are discussed. In the absence of pulmonary lesion in the case reported here, no identification to the syndrome isolated by Liebow seems permitted. The authors offer a new denomination for this unusual entity.

Aged↗
PubMed1976

Study of an inhibiting factor of epidermal proliferation in plucked skin and various tumours of mice.

The aim of our research was to investigate, by autoradiographic methods, the presence of an inhibitory factor (IF) in normal skin, in plucked skin and in five experimental skin tumors of the mouse, capable of inhibiting epidermal proliferation. The experimental model used was that of Bullough & Laurence (1960), i.e. a wound in the ear of a mouse. After tritiated thymidine administration the measurement of the labelling index confirmed the existence of an inhibitory substance in normal skin. The plucked skin had no inhibitory effect when it was taken 24 h after plucking, but after 4 days its effect had returned to normal. The skin tumours, whether epithelial or mesenchymal, showed the same inhibitory effect as normal skin whereas a non-cutaneous tumour tested had no inhibitory effect.

Animals↗
PubMed1975

[Pemphigus induced by D-penicillamine in rheumatoid arthritis. Study of 5 cases and systematic study of anti-intercellular substance antibodies of the skin in the course of treatment].

The authors present 5 cases of pemphigus induced by D-penicillamine in a series of 180 cases of rheumatoid arthritis treated with this medication. In addition, anti-epidermal intercellular substance antibodies were sought in 40 asymptomatic patients. No antibodies were found in this group. The notion of induced pemphigus seems well established, as is the value of testing for antibodies in the surveillance of D-penicillamine treatment.

Adult↗