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Biomedical subjects

J Becker

Publications and source records attributed to J Becker.

At least 37 records · Page 2Linked to original sources
PubMed1991

[Thiopental concentrations in the whole blood of pregnant and non-pregnant patients in the first minutes following injection. Forensic aspects].

Thiopentone concentrations in blood following injection of the induction solution (Thiopental, 2.5%) may be critical in the context of lethal complications arising during induction of anaesthesia and thereby the toxicological aspects of this drug can become an issue in forensic considerations. The study was designed to find out whether the dose of injected thiopentone may be calculated from blood levels measured in nine pregnant and ten non-pregnant patients. The doses injected ranged from 4-5 mg per kg body weight. The drug was administered as a single bolus dose to the patients undergoing Caesarean section. In the non-pregnant group the first dose of thiopentone was given over 25 s. After that repeated doses of 50 mg were injected over 2s every 20s until the eyelid reflex was ceased. Blood samples for determination of thiopentone were withdrawn from an indwelling catheter inserted to a large cubital vein in the arm opposite that used for the injection and thiopentone levels were measured from blood after column extraction (Extrelut) using spectrophotometry. Venous peak values were found 40-115s after injection in the Caesarean group (mean: 20.3 micrograms kg-1) and were higher than in the non-pregnant patients (97-190s, mean: 17.8 micrograms kg-1). No correlation was found regarding venous peak levels (mgkg-1 blood) and induction dose (mgkg-1 body weight), neither in the pregnant nor in the non-pregnant group. Our findings would suggest that the injected thiopentone dose cannot be calculated from the concentration of the drug in the blood. Forensic conclusions concerning the onset of lethal complications during the induction of anaesthesia cannot be drawn on the grounds of venous thiopentone concentrations.

Adult↗
PubMed1991

The screen for caregiver burden.

The Screen for Caregiver Burden (SCB) is a measure designed to identify distressing caregiver experiences rapidly. The 25-item SCB, created specifically for spouse caregivers of Alzheimer's care recipients, provides scores for objective burden (OB; number of potentially negative experiences) and subjective burden (SB; appraised distress in response to the experiences). Three separate studies (total N = 191) demonstrate the internal consistency, test-retest reliability, and validity (content, divergent, convergent, and criterion) of the scales. Finally, evidence suggests that changes in OB and SB over time are explained by changes in care-recipient functioning and caregiver distress.

Aged↗
PubMed1991

Distribution of collagens type V and VI in the normal human alveolar mucosa: an immunoelectronmicroscopic study using ultrathin frozen sections.

The ultrastructural localization of collagens type V and VI in normal human gingival mucosa was investigated by immunoelectron microscopy. Twenty biopsies were fixed in dimethylsuberimidate and shock-frozen in slush nitrogen. Collagen type V was mainly located to meshworks of uniform nonstriated microfibrils of 12 to 20 nm width, which preferentially appeared in larger spaces between cross-striated major collagen fibrils. Occasionally single microfibrils of collagen type V fanned out from the ends of major collagen fibrils, which may indicate a role as a core fibril. Collagen type V was not found in the subepithelial basement membrane and the immediately adjacent stroma. Collagen type VI was detected in a loose reticular network of unbanded microfilaments that were morphologically distinguishable by knoblike protrusions every 100-110 nm. These microfilaments were found in the vicinity, but not as an intrinsic component, of the subepithelial basement membrane. Single filaments of collagen type VI filaments appeared to form bridges between neighboring cross-striated major collagen fibrils, suggesting an interconnecting role for this collagen type. The method presented appears to be excellently suited to study the normal and pathological supramolecular organization of the oral extracellular matrix.

Adolescent↗
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↗