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Biomedical subjects

M E Jacobs

Publications and source records attributed to M E Jacobs.

At least 19 recordsLinked to original sources
PubMed2005

Evaluation of transgenic approaches for controlling tuber moth in potatoes.

A wide spectrum of strategies to genetically engineer potato plants resistant to potato tuber moth, Phthorimaea operculella (Zeller), have been investigated. The potato cv Iwa was transformed with a range of genes under the transcriptional control of the CaMV 35S promoter using Agrobacterium-mediated gene transfer. The transferred genes encode protease inhibitors (spleen inhibitor and alpha1-antitrypsin inhibitor), biotin-binding proteins (avidin and streptavidin) and Cry proteins (crylAc9, cry1Ba1, crylCa5 and cry9Aa2). Of these three transgenic approaches, cry genes have proved the most useful. In order to control the expression of the cry genes in foliage and not in the tubers a light-inducible Lhca3 promoter from potato was also used. The interaction of different cry genes was investigated using an experimental approach to simulate gene pyramiding in potato. Potato plants transgenic for both the crylAc9 and cryAa2 genes were developed and evaluated to help provide a more durable resistance to potato tuber moth.

Animals↗
PubMed1996

Two supernumerary marker chromosomes, derived from chromosome 6 and 9, in a boy with mild developmental delay.

We report on a boy with two supernumerary marker chromosomes which were identified by fluorescence in situ hybridization and derived from chromosome 6 and 9. In lymphocytes, a mosaic karyotype was found: 46,XY (17%)/ 47,XY,r(6) (24%)/47,XY,r(9) (20%)/48,XY,r(6),r(9) (39%). Only minor dysmorphic features and mild developmental delay were present. Despite extensive fluorescence in situ hybridization studies using a large panel of probes, we were unable to characterize the marker chromosomes in more detail, mainly because no probes for the chromosome regions involved were available to us. In order to reach a better understanding of the clinical relevance of small supernumerary marker chromosomes, it will be necessary to create a widely available set of probes, covering all chromosome regions.

Child, Preschool↗
PubMed1996

Medical UV exposures and HIV activation.

This paper presents the first attempt to evaluate the potential of clinical UV exposures to induce the human immunodeficiency (HIV) promoter and, thus, to upregulate HIV growth in those skin cells that are directly affected by the exposure. Using the data for HIV promoter activation in vitro, we computed UVB and psoralen plus UVA (PUVA) doses that produce 50% of the maximal promoter activation (AD50). Then, using (a) literature data for UV transmittance in the human skin, (b) a composite action spectrum for HIV promoter and pyrimidine dimer induction by UVB and (c) an action spectrum for DNA synthesis inhibition by PUVA, we estimated the distribution of medical UVB and PUVA doses in the skin. This allowed us to estimate how deep into the skin the HIV-activating doses might penetrate in an initial and an advanced stage of UVB or PUVA therapy. Such analysis was done for normal type II skin and for single exposures. The results allow us to predict where in the skin the HIV promoter may be induced by selected small and large therapeutic UVB or PUVA doses. To accommodate changes in skin topography due to disease and UV therapy, our considerations would require further refinements. For UVB we found that, when the incident dose on the surface of the skin is 500 J/m2 (290-320 nm) (initial stage of the therapy), the dose producing 50% of the maximal HIV promoter activation (ADUVB50) is limited to the stratum corneum. However, with an incident dose of 5000 J/m2 (an advanced stage of the therapy), ADUVB50) may be delivered as far as the living cells of the epidermis and even to some parts of the upper dermis. For PUVA we found that, when the incident UVA doses are 25 or 100 kJ/m2 (320-400 nm) (an initial and an advanced stage of therapy, respectively), and the 8-methoxypsoralen concentration in the blood is 0.1 microgram/mL (the desired level), the combined doses to the mid epidermis (and some areas of the upper dermis) are well below the 50% HIV promoter-activating PUVA dose (ADPUVA50). Only under the worst scenario conditions, i.e. an exceptionally high drug concentration in the patient's tissues and localization of HIV in the nearest proximity to the skin surface, would the combined PUVA dose expected during photochemotherapy exceed ADPUVA50. These results suggest that the probability of HIV activation in the epidermis by direct mechanisms is higher for UVB than for PUVA treatment. However, complexities of the UV-inducible HIV activation and immunomodulatory phenomena are such that our results by themselves should not be taken as an indication that UVB therapy carries a higher risk than PUVA therapy when administered to HIV-infected patients.

HIV↗
PubMed1994

Partial trisomy and monosomy 8p due to inversion duplication.

Fluorescent in situ hybridization with probes specific for a chromosomal subregion and chromosome-specific libraries (chromosome painting) are important new methods for assessing chromosome rearrangements. In this paper we present four patients with additional chromosomal material on chromosome 8p who have been studied using G-banding techniques, chromosome painting and FISH with cosmid probes specific for the region 8p23.1-->8pter. In all cases we found a partial inversion duplication of 8p along with a deletion of the region 8p23.1-->8pter.

Adult↗
PubMed1992

[Experiences with arthrotomy of the knee in day care].

A retrospective study was performed of patients who had undergone an open knee procedure treated as day cases at the Regional Hospital of Zevenaar. An analysis was made of the rate of complications, whether complications were treated adequately, and how patients experienced an arthrotomy of the knee as a day-case procedure. Eighty-seven healthy patients aged 15 to 50 years underwent an arthrotomy of one knee as a day-case procedure, secondary to a diagnostic arthroscopy. The mean follow-up period was 8 months. Patients were reviewed by questionnaire, after which the knee was examined. The number of complications (6) was comparable with those reported in the literature. Complications within a few days after operation were reported to the GPs, who either treated themselves, or referred patients to the hospital. Of the patients 76% preferred this procedure to an operation in a clinical setting. The amount of pain suffered appears to be of great influence on the preference of the patient. The results of this study demonstrate that an arthrotomy of the knee is feasible as a day-care procedure, although extensive pre- and postoperative instructions to the patients may be improved.

Adolescent↗
PubMed1991

Measles control in the urbanising environment.

The relationship between urbanisation and measles control is examined. In urban settings in developing regions measles is a disease of particular importance, since it tends to affect children at a younger age and with greater severity than in rural settings. A further finding in urban areas, especially peri-urban slums, is the lower measles vaccination coverage rates compared with rural regions. Factors identified as determinants of measles vaccination coverage among children under 2 years of age in urban areas include: home delivery; being born outside the urban setting; and length of stay in the city. These factors are probably related to the low socioeconomic status and lack of social integration experienced by new urban immigrants. A number of additional obstacles, such as distance, economic and cultural barriers, and inconvenient clinic hours all prevent parents from gaining easy access to vaccination services. In order to address the problems of measles control in expanding urban settings, a regional approach--with full integration of curative and preventive services--is called for. A more effective use of existing services will probably go a long way towards improving urban vaccination coverage with resultant measles control.

Health Services Accessibility↗
PubMed1989

Survey of oral fluid therapy practices in South Africa.

The objectives of this study were to document the official oral fluid therapy (OFT) policies of all the ministries of health in South Africa and of the four provincial authorities, to determine what methods of OFT are used in hospitals providing paediatric care, to determine the OFT methods recommended by hospital staff for use at home, to establish the level of support for the idea of one national policy for OFT and to determine what senior academic paediatricians think about these issues. We conducted structured telephonic interviews of professional staff in charge of paediatric wards in 159 randomly selected hospitals providing general inpatient care. The hospitals were stratified as private, provincial and 'homeland'. We also interviewed the directors-general or the secretaries or their deputies in each ministry of health as well as directors of hospital services or their deputies in each one of the four provinces of the Republic. Lastly, we spoke to the academic heads of paediatric departments in each of the country's eight medical schools. The results show that the use of OFT for inpatient care of diarrhoeal disease is far from universal, and that the picture with regard to promotion of home OFT is even less favourable. We identified an unacceptable diversity in the OFT methods being promoted as well as a degree of resistance to the development of one national policy. We recommend that one policy, based on the recommendations of the South African Paediatric Association, be adopted by all health authorities in South Africa as a matter of urgency.(ABSTRACT TRUNCATED AT 250 WORDS)

Fluid Therapy↗
PubMed1989

Plain radiographs inadequate for evaluation of the cement-bone interface in the hip prosthesis. A cadaver study of femoral stems.

To determine whether plain radiographs accurately represent the true cement-bone interlock, a comparison was made between radiographs and macroscopic morphology on cross sections of 11 human femora into which a cemented endoprosthesis had been inserted. Four femora had been retrieved postmortem from patients with a hip arthroplasty, and seven cadaver femora were cemented under varying conditions. All the femora were radiographed and then cut for macroscopic inspection of the cement-bone interface with respect to gross interposition, depth of cement penetration, integrity of the bone bed, and lamellation of the cement.

Bone Cements↗
PubMed1987

An urban strategy towards the EPI.

Rapidly increasing urbanisation, fragmentation of health services, and civil unrest can constitute threats to the efficiency of the excellent immunisation services developed in most South African cities. Among children attending hospital outpatient departments are many who have escaped the net of the preventive services. A system has been developed to immunise all children entering the Red Cross War Memorial Children's Hospital, Cape Town, in whom immunisation is incomplete for age. The Community Health Liaison Group, which co-ordinates these and other health preventive/promotive activities in the hospital, is described.

Child, Preschool↗
PubMed1984

The FDA report on intraocular lenses.

Clinical studies of intraocular lenses (IOLs) as investigational devices have been regulated in the United States by the Food and Drug Administration (FDA) since 9 February 1978. As of August 1982, data have been collected on more than one million IOLs implanted. During the last 12 months of the study, 409 000 IOLs were implanted. Visual acuity of 20/40 or better at one year after surgery was present in 85% of over 45 000 cases reviewed. Increasing patient age, surgical problems, postoperative complications, and adverse reactions were factors that reduced the visual acuity. The current trend in the USA is for implantation of posterior chamber and anterior chamber IOLs.

Cataract Extraction↗
PubMed1983

The FDA report on intraocular lenses.

Clinical studies of intraocular lenses (IOLs) as investigational devices have been regulated in the United States by the Food and Drug Administration (FDA) since February 9, 1978. As of August 1982, data have been collected on more than one million IOLs implanted. During the last 12 months of the study, 409,000 IOLs were implanted. Visual acuity of 20/40 or better at one year after surgery was present in 85% of over 45,000 cases reviewed. Increasing patient age, surgical problems, postoperative complications, and adverse reactions were factors that reduced the visual acuity. The current trend in the USA is for implantation of the posterior chamber and anterior chamber IOLs.

Aged↗
PubMed1982

Beta-alanine and tanning polymorphisms.

1. Beta-alanine is found in mycelial walls of mature tan, but not immature white, stage of Morchella esulenta, nor in any stage of a permanently white mutant. 2. Beta-alanine is also found in hydrolysed water-extracts of human hair, the concentration being higher in blond than in dark brown, and in pigmented than in unpigmented hair. 3. Beta-alanine, added to tyrosinase-oxidized tyrosine, dopa, or dopamine has only a slight yellowing influence on the final black pigment; but when the amino group of tyrosine is combined with leucine, added beta-alanine produces stable tan pigments. 4. With L-alanine substituted for beta-alanine in this reaction, green pigment results. 5. Gelatin filters stained with the tan pigment allow solar heating of underlaying water more quickly than do those stained with the black pigment. Unstained filters allow such heating even more quickly. 6. Beta-alanine enhances production of tan pigment when heated with the phospholipid, lecithin. Implications for pigmentary adaptation, and formation of lipofuscin-like age pigments are discussed.

Aging↗
PubMed1980

Influence of beta-alanine on ultrastructure, tanning, and melanization of Drosophila melanogaster cuticles.

In Drosophila melanogaster, the chitinous microfibrils arising from the tips of the epidermal villi in adult cuticles remain irregular and loose in the mutant ebony (which fails in cuticular incorporation of beta-alanine) but closely knit and regular in normal flies. Addition of beta-alanine to cuticles from which nonchitinous materials have been removed with alkali converts the loose arrangement of the microfibrils to a compact and sharply delineated arrangement. beta-alanine also accelerates tyrosinase-catalyzed oxidation of N-acetyldopamine by reacting with the oxidized product of the reaction to produce an orange-red complex. Similarly, beta-alanine accelerates oxidation of N-acetyldopamine when these two substances are added to fluids from the hemocoel, to lead to tanning instead of normal blackening. These findings may help explain why beta-alanine induces tanning while inhibiting melanization in insects.

Alanine↗
PubMed1978

Influence of beta-alanine on mating and territorialism in Drosophila melanogaster.

Effects of beta-alanine on mating behavior and aggression were studied in Drosophila melanogaster using the following competitive pairs: (1) homozygous black (b/b) flies, in which beta-alanine synthesis is decreased, vs. alanine is blocked vs. wild-type (e+/e+) flies; (2) dark flies, in which beta-alanine incorporation is reduced, owing mainly to chromosome 3, vs. light flies collected from the same population as were the dark flies; (3) homozygous black (b/b) flies, in which beta-alanine synthesis is decreased, vs. beta-alanine-infected b/b flies, which are phenocopies of wild-type flies. The behavior of mixed-sex groups was studied in a large, illumination-graded observation chamber containing food and in small uniformly illuminated cells also containing food. The relative competitive mating abilities of these types were measured in both experimental conditions. Uninjected black flies, but not injected ones, showed weak and unsteady gait and weak wing extension. In ebony these abnormalities were more extreme. Dark flies did not show these abnormalities. Accelerated sexual maturation was indicated in males by early onset of courtship and enhanced territorial aggression and in females by earliness of mating. Such acceleration was observed in ebony and dark flies, compared with light flies, and among beta-alanine-injected b/b flies competing with uninjected black flies. Ebony males, although maturing earlier than wild-type males, were less successful than wild-type males in mating. This difference was even greater when the flies were all allowed to mature before competing. Ebony females outmated wild-type females. Dark flies outmated light flies, and beta-alanine-injected b/b males outmated uninjected black males, especially in bright light. Ebony flies mated much longer than wild-type flies, and black flies mated slightly longer than injected b/b flies. There was some spatial isolation of ebony from wild type, dark from light, and beta-alanine-injected from uninjected b/b flies in the illumination-graded observation chamber. Ebony flies more than wild type concentrated near food. Flies were attracted to the current of moist inlet air. They were also attracted to deposited excrement, and males defended such deposits as a mating area, thus showing rudiments of arena behavior in which a mating area away from the oviposition site is defended. Usually, however, the defended area focused on food.

Aggression↗