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Biomedical subjects

J Becker

Publications and source records attributed to J Becker.

At least 73 records · Page 4Linked to original sources
PubMed1991

Immunoelectron microscopic localization of collagens type I, V, VI and of procollagen type III in human periodontal ligament and cementum.

We examined the ultrastructural localization of collagens Type I, V, VI and of procollagen Type III in decalcified and prefixed specimens of the periodontal ligament and cementum, by immunoelectron microscopy using ultra-thin cryostat sections. Immunostaining for collagen Type I was pronounced on the major cross-striated fibrils entering cementum and in cementum proper, whereas staining for procollagen Type III was almost exclusively observed on the major fibrils in the periodontal ligament situated more remote from cementum. Reactivity for collagen Type V was limited to aggregated, unbanded filamentous material of about 12 nm diameter that was found mainly in larger spaces between bundles of cross-striated collagen fibrils and occasionally on single microfibrils that apparently originated from the ends of the major collagen fibrils, which may support the concept of this collagen as a component of core fibrils. Collagen Type VI was present as microfilaments appearing to interconnect single cross-striated fibrils. In the densely packed fibril bundles of the periodontal ligament, no collagen type VI was detected. Neither Type V or Type VI collagen was observed in cementum.

Adolescent↗
PubMed1991

EEG and skeletal development in children with different psychosocial characteristics.

Two groups of children with different socioeconomic level were studied. One minute EEG at rest was recorded in monopolar leads F3, F4, C3, C4, P3, P4, O1, O2, F7, F8, T3, T4, T5 and T6. Absolute and relative power in four EEg bands (delta, theta, alpha and beta) were computed. Radiographies of the left hand and the wrist were also obtained in all children. Age regression equations of the variables derived from EEG spectra were calculated in each group. In the group with low socioeconomic level many children had antecedents of risk factors. In this group absolute and relative power in the four bands presented a great dispersion and no correlation with age. In the group with good socioeconomic level the age regression equations of the EEG variables were significant, absolute values in the four bands decreased with age, as well as delta and theta relative power, while alpha and beta relative power increased with age. The area of the ossification center of each bone of the hand of the lower end of the ulna and radius were obtained from the X-ray film. Linear regression equations for the area of each ossification center were significant in both groups. No intercept or slope differences existed between both groups in any area. It is concluded that psychosocial disadvantage and antecedents of risk factors, although not producing any effect on skeletal development, do affect EEG maturation.

Adolescent↗
PubMed1991

On the mechanism of action of H2O2 in the cellular stress.

We propose a hypothesis according to which the reactive and reduced species of oxygen could be the intracellular inducers of the stress (or "heat-shock") response. This hypothesis is based on the following observations on Drosophila cells: a) the return to normoxia after 24 h anaerobiosis is sufficient to induce the synthesis of the "heat shock" proteins without elevation of temperature together with a rapid increase of O2 consumption; b) hydrogen peroxide introduced in the culture medium induces the early transcriptional activation of the "heat shock" genes (maximal after 5 minutes); c) hydrogen peroxide added to cellular extracts in vitro (thus acting as an intracellular metabolite) activates instantaneously the binding capacity of a "heat shock" factor to a DNA "heat shock" regulatory element. Thus, hydrogen peroxide, and possibly other reactive reduced species of oxygen, could trigger the onset of the stress (or "heat shock") response.

Animals↗
PubMed1991

An improved technique for the in situ detection of DNA after polymerase chain reaction amplification.

In situ detection of polymerase chain reaction (PCR)-amplified DNA in cell and tissue preparations previously required 5 to 7 primer pairs designed to generate a long (greater than 1,000 base pair) product. The authors describe a nonisotopic PCR in situ technique, employing a single primer pair and target sequences as short as 115 base pairs, that can detect one target molecule per cell. The essential procedural change is to withhold the DNA polymerase or primers until the reaction temperature approaches 80 degrees C. The Hot-Start method greatly increased amplification specificity which, more than product size, appears to determine success of in situ PCR. The marked improvement in specificity may permit target detection by direct incorporation of labeled nucleotides.

DNA, Viral↗
PubMed1991

Ecdysterone decreases the transcription level of the retrotransposons 1731 and 412 in a Drosophila cell line.

Cultured Drosophila melanogaster cells are responsive to the steroid hormone 20-hydroxyecdysone (ecdysterone). The transcripts of two copia-like transposable elements, 412 and 1731 were examined in cells treated for different lengths of time by the hormone. Using dot-blot and Northern-blot analysis, we have shown that the transcripts of these two retrotransposons were rapidly decreased by ecdysterone treatment.

Animals↗
PubMed1991

Combined Fontana-Masson-mucin staining of Cryptococcus neoformans.

Cryptococci react positively with various histochemical stains, including the Fontana-Masson (FM), which stains the cell wall, and mucin stains, such as alcian blue and mucicarmine, which stain the capsule. Combinations of the FM stain with both the alcian blue and mucicarmine stains were performed on paraffin-embedded tissue specimens that were obtained from 15 patients who had culture-proved cryptococcosis. Combined FM-mucicarmine and FM-alcian blue stains were compared with other individual fungal stains. The FM stain, followed by either the mucicarmine or alcian blue stain, distinctively demonstrated both the cell wall and capsule of most organisms. More organisms were recognized in the combined stains than with either stain done individually. No interference between the stains was noted. Combining the FM stain with either of these two mucin stains appears to be helpful for identifying cryptococci.

Alcian Blue↗
PubMed1991

HIV-1 seropositivity and behavioral and sociological risks among homosexual and bisexual men in six Mexican cities.

We report on the epidemiology of sexual behaviors, HIV-1 seroprevalence, and condom use in gay and bisexual men in six Mexican cities in 1988 and test the extent to which variations in sexual behavior and sociological risks are responsible for variations in prevalence. Seroprevalence rates among samples in six cities ranged from 2% to 25%. In multiple logistic regression models controlling for city, insertive/receptive behavior (IRB), and meeting partners in bathhouses, the following were independently related to seropositivity (p less than 0.05): city, IRB, syphilis, sex with a person with AIDS, and meeting partners in bathouses. The independent risks associated with categories of IRB were no or almost no activity (odds ratio 1.0), only insertive (3.0), mostly insertive (4.9), mixed (6.0), mostly receptive (3.3), and only receptive (0.9). The condom use rate on last sexual encounter was 30%. The main sexual risk for HIV-1 infection is not exclusively receptive anal sex, but rather mixed behavior. This association may be explained by the infectious state of the partner pools. The sociologic risk variables (national and local partner pools) are better predictors of seroprevalence than behavioral variables, such as the number of partners or use of condoms. These results imply that more effective individual strategies for risk reduction are needed, including better knowledge concerning the risk status of partners.

Adolescent↗
PubMed1990

Undulin, an extracellular matrix glycoprotein associated with collagen fibrils.

Undulin, a novel noncollagenous extracellular matrix protein, was isolated from skin and placenta. In polyacrylamide gels most of the unreduced protein migrates with Mr above 1,000,000 yielding bands A (Mr 270,000), B1 (Mr 190,000), and B2 (Mr 180,000) after reduction. Undulin is biochemically and immunochemically distinct from other previously characterized large matrix glycoproteins. Immunoblotting using monoclonal antibodies suggests that bands A and B are closely related. Electron microscopy reveals undulin as structures consisting of an approximately 80-nm-long-tail with a nodule on one end and with one or two shorter arms on the other. Ultrastructurally immunolabeled undulin is found mainly between densely packed mature collagen fibrils. Indirect immunofluorescence shows bundles of uniform wavy fibers in dense connective tissues superimposable on a subpopulation of type I collagen structures. This suggests that undulin serves a specific yet unknown function in the supramolecular organization of collagen fibrils in soft tissues.

Amino Acids↗
PubMed1990

Hydrogen peroxide activates immediate binding of a Drosophila factor to DNA heat-shock regulatory element in vivo and in vitro.

The synthesis of heat-shock proteins via activation of heat-shock genes occurs in response to heat and various physical or chemical stressing agents. Transcriptional activation of heat-shock genes requires a heat-shock regulatory element in their promoter, to which a heat-shock specific transcription factor binds. In Drosophila cells, the heat-shock factor already exists in unstressed cells in an inactive form and acquires the capacity to bind to the heat-shock element following stress. The mechanism of this activation is not known: neither is it known whether the different stressing agents induce the heat-shock response through a common mechanism. We previously proposed that many agents known to induce the heat-shock response (substances interfering with respiratory metabolism, agents reacting with sulphydryl groups, metals, recovery from anaerobiosis and ischemia) might act via accumulation of reactive oxygen species, i.e. superoxide ion or H2O2. We show here that H2O2, introduced either in Drosophila cell cultures or in cell extracts, was able to activate heat-shock-element binding. Activation was rapid and H2O2 concentration dependent, with a threshold of 1 microM. These results were confirmed with mouse fibroblast cells. This very rapid activation, in vivo or in vitro, suggests a direct effect of H2O2 either on the heat-shock factor itself or on its activator.

Amino Acid Sequence↗
PubMed1990

Effect of sex, psychosocial disadvantages and biological risk factors on EEG maturation.

Broad-band frequency analysis was performed on the EEGs of school-age children in order to study the effects of sex, socioeconomic status (SES) and biological risk factors on EEG maturation. Absolute power and relative power in delta, theta, alpha and beta frequency bands were computed in monopolar recordings from F3, F4, C3, C4, P3, P4, O1, O2, F7, F8, T3, T4, T5 and T6. Total absolute power and power in the delta and theta bands decreased with age, following a quadratic polynomial expression. Relative power followed a linear regression with age. Delta and theta decreased while alpha and beta increased. Sex differences in relative power were observed, possibly related to a pubertal spurt: slopes of regression equations were steeper in girls than in boys. Children from low SES (very low income and/or illiterate mother) had higher values of absolute power and a higher percentage of delta and lower of alpha than children with good SES, suggesting a maturational lag. A group of children with personal antecedents of risk factors associated with brain damage were compared with children without antecedents. The former group had higher values of absolute power. Depending on the severity of the risk, children with more severe antecedents had greater differences from children with no antecedents than children in whom antecedents were considered as slight. Risk antecedents had no effect on relative power.

Age Factors↗
PubMed1990

Melanotic neuroectodermal tumor of infancy.

The case of a 2-month-old male infant treated for melanotic neuroectodermal tumor of infancy is presented to demonstrate the importance of early treatment in the containment of the growth of such lesions. Although the lesion itself is rare, the posterior maxillary location and involvement of the optic nerve in this patient's lesion made his case even less typical of those commonly documented in the literature. Complete surgical excision of the lesion was not possible in this patient because of the gross mutilation it would have caused. There was no evidence of the tumor recurring in 18 months of follow-up examinations. These results support the current theories regarding the debulking effect in conjunction with bodily defenses on residual tumor cells and the effect of the removal of stimulatory cells on invading peripheral cells. This case points out the importance of an early and rapid investigation of a mass that initially occurs on the alveolar ridge of an infant.

Humans↗
PubMed1990

Production and enhanced anti-tumor activity of tumor necrosis factor in mice treated with cyclophosphamide.

We demonstrated recently that the production of tumor necrosis factor (TNF) is induced in normal mice and in the immunosuppressed nude mouse model by the administration of muramyl dipeptide (MDP) derivatives followed by endotoxin (lipopolysaccharide). In the present study, the ability of this treatment to induce the production of TNF in mice receiving cyclophosphamide (CY) was examined. Two days following treatment with high-dose CY (250 mg/kg), mice exhibited leukocytopenia and drastically reduced splenic weight. However, these animals remained capable of producing TNF, albeit at lower levels, when treated with MDP derivatives and lipopolysaccharide (LPS), particularly when the lipophilic analogue MDP-dipalmitoyl glycerol (GDP) was utilized. TNF was also induced by the administration of MDP-GDP and LPS to Meth A sarcoma-bearing mice treated with this dose of CY. Furthermore, in all animals receiving this combination therapy, sarcoma necrosis and complete regression were obtained without any sign of tumor regrowth. A dose of 100 mg/kg CY was not effective for inhibiting tumor regrowth under the same experimental conditions. These results demonstrated that the anti-tumor activity of endogenously induced TNF is potentiated by combined therapy with a high dose of CY.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1990

Coping resources and depression in the caregiving spouses of Alzheimer patients.

This study deals with the self-rated impact of caring for a spouse with Alzheimer's disease at home. Impacts on the caregiver's marriage, work, recreation and mood were investigated as a function of the patient's disability level and of the coping resources which caregivers reported were available to and/or used by them. The patient's disability level had a more negative impact on the caregiver's marriage and recreation than did the coping resource variables whereas the reverse was true for work. The caregiver's work was the only life area in which the availability and mobilization of coping resources influenced the caregiver's level of depression. To clarify these results, additional regression analyses were conducted separately for homemakers and employed subjects. While mobilized coping resources (social activity level and homemaking activity level) were correlated with depression among homemakers, none of the indicators of mobilized coping resources was correlated with depression among workers. These findings suggest that the role in which stress occurs is an important factor in understanding stress and the coping process.

Adjustment Disorders↗
PubMed1990

[Biostimulation of wound healing in rats by combined soft and middle power lasers].

For some time now, the combined soft- and middle-power laser has been used for treating wounds and various skin diseases, but its effect has not yet been confirmed in experiments on animals. For this reason, a controlled test on the effect of this laser on wound healing in rats was conducted. In 16 rats, 3-cm long skin incisions were made on the wall of the abdomen and then sutured using standard surgical technique with 5 stitches. Eight rats were then treated with laser light, the other 8 receiving a control treatment. The wounds were photographed on the 1st, 2nd, 3rd, 5th, 8th and 15th postoperative day. The photographs were shown to 10 doctors who rated the wounds from 1 to 4 on the basis of the criteria inflammation and adaptation. While the wounds of the laser group were not judged to be significantly better than those of the control group in terms of inflammation, adaptation was judged to be significantly better in the laser-treated group. This effect was particularly evident at the beginning of treatment (3rd day: average rating of laser group: 1.68; S = 0.32; control group: 2.41; S = 0.53; analysis of variance parameters for repeated measurements: p = 0.027 less than 0.05). These results demonstrate that in all probability the combined soft- and middle-power laser promotes the closing of wounds in rats, especially in the first postoperative days, while there is no positive effect on inflammation.

Animals↗
PubMed1990

Correlation between EEG spectral parameters and an educational evaluation.

EEG spectral parameters were computed in a group of children with different degrees of difficulty in learning to read and write. For statistical analyses, Z-transformed values according to normative age-regression equations were used to control the age effects. Canonical Correlation Analysis between absolute power in different bands and the categories of the educational evaluation (good, regular, poor and very poor) showed that more delta was probably related to a poor evaluation and more alpha in occipital areas to a good one. MONOVA also showed highly significant differences in the absolute power in many leads between children with different evaluations. As children with a poor evaluation very frequently had antecedents of risk factors related to brain damage and were from a low socioeconomic status, and both factors have been shown to affect absolute power, it may be that the differences observed were due to these causes. However, relative power correlated more with the learning problems. Children with minor difficulties, with no antecedents and with good socioeconomic status had more theta in almost all leads than children with a good evaluation and with the same characteristics. Children with a poor, or very poor, evaluation had more delta in left frontal and temporal areas (F3, F7 and T3) which may reflect underlying cerebral dysfunction of these regions directly involved in reading and writing processes.

Child↗
PubMed1990

Brainstem evoked potentials in learning disabled children.

Averaged brainstem auditory responses (BAER) were recorded using left and right ear stimulation with clicks of 90 dBs in two groups of primary school children (control and learning disabled). A linear multiple regression model was used in an attempt to demonstrate the effects of sex, high risk factors related to brain damage and learning disability on the evoked responses. Sex showed a strong influence in the latencies of the first five peaks, with girls having shorter latencies. Risk factors had an effect on the latency of peak V, the I-V interval and the V/I amplitude ration, but only when the left ear was stimulated. Learning disability had no significant influence according to this analysis. Multivariate test of complete homogeneity showed highly significant differences between LD and control boys when the left ear was stimulated and between control and LD girls when the right ear was stimulated. Principal component analyses revealed differences between the two groups: the BAER components of the control subjects showed a minor source of variance when the right ear was stimulated. A contrary effect was observed in LD children. Such differences might be related to ear preference and hemispheric dominance.

Acoustic Stimulation↗