Biomedical subjects

G Oliver

Publications and source records attributed to G Oliver.

At least 73 records · Page 4Linked to original sources

PubMed1997

Tuberculosis notifications in Australia, 1995.

This is the fifth annual report of the National Mycobacterial Surveillance System (NMSS), for new and relapsed cases of tuberculosis notified to State and Territory health authorities in 1995. Cases of atypical mycobacterial infection notified to the scheme are also briefly summarised. The notification rate for new cases of tuberculosis was 5.47 per 100,000 population, and for relapsed cases 0.28 per 100,000. These rates have remained stable for a number of years in Australia, and are low compared with rates in other countries. Some identifiable groups in the Australian community continue to experience higher rates of tuberculosis, including members of indigenous communities and some groups born overseas. Surveillance through the NMSS has a major role to play in the control of tuberculosis.

Adolescent↗

PubMed1997

The Pax4 gene is essential for differentiation of insulin-producing beta cells in the mammalian pancreas.

The mammalian pancreas contains two distinct cell populations: endocrine cells which secrete hormones into the bloodstream, and exocrine cells, which secrete enzymes into the digestive tract. The four endocrine cell types found in the adult pancreas-(alpha, beta, delta and PP-synthesize glucagon, insulin, somatostatin and pancreatic polypeptide, respectively. All of these endocrine cells arise from common multipotent precursors, which coexpress several hormones when they start to differentiate. Expression of some homeobox genes in the early developing pancreas has been reported. The Pax4 gene is expressed in the early pancreas, but is later restricted to beta cells. Inactivation of Pax4 by homologous recombination results in the absence of mature insulin- and somatostatin-producing cells (beta and delta, respectively) in the pancreas of Pax4 homozygous mutant mice, but glucagon-producing alpha cells are present in considerably higher numbers. We propose that the early expression of Pax4 in a subset of endocrine progenitors is essential for the differentiation of the beta and delta cell lineages. A default pathway would explain the elevated number of alpha cells in the absence of Pax4.

Animals↗

PubMed1997

Current views on eye development.

Several genes involved in the regulation of eye development in different species have been identified. Structural and functional conservation have been found between some of these genes in organisms as diverse as Drosophila and mouse. One notable example is the relationship between the mouse Pax6 gene and eyeless of Drosophila. Ectopic expression of eyeless or mouse Pax6 in Drosophila results in the formation of additional eyes. Recently, another homeobox gene, Six3, was found to promote ectopic lens formation in fish embryos. The next step will be to unravel the associated regulatory pathways of these genes and assess the degree to which they display evolutionary conservation. This will be important in order to assimilate these findings with current anatomical and embryological models. It seems reasonable to believe that in the near future the characterization of the whole framework required for vertebrate eye development will be accomplished.

Animals↗

PubMed1997

Influence of bile on beta-galactosidase activity and cell viability of Lactobacillus reuteri when subjected to freeze-drying.

The effect of bile on beta-galactosidase activity and cell viability was investigated using two strains of Lactobacillus reuteri that were subjected to freeze-drying. In the presence of 0.15% oxgall, beta-galactosidase activity of the whole cells was significantly increased. After lyophilization, the cultures that had been treated with oxgall showed a low survival rate without changes in beta-galactosidase activity. The poor resistance of the cells to damage from freeze-drying might be related to the presence of membranous structures containing simple folds and buds of the cell membrane, as was observed by transmission electron microscopy.

Bile↗

PubMed1996

Psychosexual development of women with congenital adrenal hyperplasia.

Women with congenital adrenal hyperplasia (CAH) (N = 31) and their unaffected sisters or female cousins (N = 15) participated in a study of psychosexual development. All participants were > or = 18 years of age (mean age, 25 years; range, 18-40). Comparisons were also made between the CAH women with the salt-wasting (SW) form of the disorder and those with simple virilization (SV). A psychosexual assessment protocol examined six variables: (1) sex assignment at birth (probands only); (2) recalled sex-typed behavior during childhood; (3) gender identity and gender role identification in adulthood; (4) relationship status; (5) sexual orientation in fantasy; and (6) sexual orientation in behavior. Salt-wasting status and sex assignment at birth were also ascertained for the CAH women who either refused to participate in the study (N = 10) or could not be traced (N = 13). Compared to the controls, the women with CAH recalled more cross-gender role behavior and less comfort with their sense of "femininity" during childhood. The two groups did not differ in degree of gender dysphoria in adulthood, although the probands showed more cross-gender role identification. Three of the nonparticipant probands were living, as adults, in the male social role (2 reared from birth as boys and 1 who changed from the female to the male social role during adolescence). The CAH women and the controls did not differ in relationship status (married/cohabiting vs. single). The CAH women had lower rates of exclusive heterosexual fantasy and fewer sexual experiences with men than the controls; however, the CAH women did not have more sexual experiences with women than the controls. Comparisons between the SW and SV revealed several differences: the SW were less likely to be assigned to the female sex at birth, recalled more cross-gender role behavior during childhood, were less likely to be married or cohabiting, and had lower rates of sexual experiences with men. The results were discussed in relation to the effects of prenatal androgens on psychosexual differentiation.

Adrenal Hyperplasia, Congenital↗

PubMed1996

Influence of Carbohydrates on the alpha-Galactosidase Activity of Lactobacillus fermentum

The influence of soybean galactosaccharides (stachyose, raffinose, melibiose) as well as galactose and glucose on the synthesis and activity of alpha-galactosidase (alpha-gal) from Lactobacillus fermentum CRL 251 was studied. Stachyose was the most effective inducer, followed by melibiose, raffinose, and galactose; scarce activity was detected with glucose. Exogenously supplied glucose inhibited the synthesis of the enzyme in cultures of L. fermentum growing on galactose. This effect was reversed by the addition of cyclic adenosine-3',5' monophosphate (cAMP), which suggests that this compound could be involved in the regulation of alpha-gal synthesis.

Journal Article↗

PubMed1996

Control of Listeria monocytogenes in ground beef by 'Lactocin 705', a bacteriocin produced by Lactobacillus casei CRL 705).

The effectiveness of Lactobacillus casei CRL 705 as well as that of Lactocin 705, the associated bacteriocin produced, in reducing population levels and growth of Listeria monocytogenes in sterile and non-sterile ground beef was studied. Predetermined numbers of L. monocytogenes and concentrations of Lactocin 705 were added to the meat slurries. Listeria in the bacteriocin-treated and control samples during incubation at 20 degrees C were enumerated as CFU on Bacto blood agar base. Results indicated that reduction in numbers of Listeria was largest with high levels of Lactocin 705 and few initial cell numbers of the pathogen present in the meat slurry. However, when the producer strain was added to the slurry, no significant inhibition was detected. Furthermore, inhibition by listeria was shown to be greater when meat slurries were heat-treated.

Animals↗

PubMed1996

Ectopic lens induction in fish in response to the murine homeobox gene Six3.

Recent findings show an unexpected conservation of genes involved in vertebrate and insect eye development. The Drosophila homeobox gene sine oculis is crucial for eye development. Its murine homologue, Six3 is expressed in the anterior neural plate, a region which is involved in lens induction in Xenopus. To examine whether Six3 participates in the process of eye formation, mouse Six3 was ectopically expressed in fish embryos. The results show that Six3 is sufficient to promote ectopic lens formation in the area of the otic vesicle and that retinal tissue is not a prerequisite for ectopic lens differentiation. Our findings suggest a conserved function for Six3 in metazoan eye development.

Animals↗

PubMed1996

Inducible transport of citrate in Lactobacillus rhamnosus ATCC 7469.

Lactobacillus rhamnosus ATCC 7469 exhibited diauxie when grown in a medium containing both glucose and citrate as energy source. Glucose was used as the primary energy source during the glucose-citrate diauxie. Uptake of citrate was carried out by an inducible citrate transport system. The induction of citrate uptake system was repressed in the presence of glucose. This repression was reversible and mediated by cAMP.

Biological Transport↗

PubMed1996

Chemical composition of the cell wall of lactic acid bacteria and related species.

In order to examine the relationship between biological activities and the cell wall content, the murein type and the teichoic acid of the cell wall from five strains of bacteria were studied. Two of these Lactobacillus casei CRL 431 and L. acidophilus CRL 730, are used in a commercial fermented milk (BIO MILK), which is believed to be beneficial for health. The other strains, Lactococcus lactis CRL 526, Pediococcus pentosaceus CRL 923 and Propionibacterium acidipropionici CRL 1198 were included in order to compare the cell wall structures of active and inactive strains. A method was designed to confirm the amino acids of the peptidoglycan in impure substrates. Four of the studied strains, L. casei, L. acidophilus, L. lactis and P. acidipropionici, contained glycerol teichoic acids. L. casei, L. acidophilus, P. pentosaceus and L. lactis contained A4 alpha type murein, while P. acidipropionici contained A3 gamma type. The capacity of orally administered peptidoglycans of the studied strains to stimulate phagocytosis by mouse peritoneal macrophages was analyzed. Only the PG of L. casei showed this activity. No differences were observed between active and inactive strains with respect to the chemical composition of the peptidoglycan. Therefore the biological activity is unlikely to be due to the peptidoglycan structure.

Animals↗

PubMed1996

The effect of methotrexate-loaded bone cement on local destruction by the VX2 tumour.

Previous studies have shown that the activity of the cytostatic drug methotrexate (MTX) embedded in acrylic cement is not affected by thermal changes in the cement. MTX is slowly released from the cement for several months and remains biologically active throughout this period. Our aim was to determine whether MTX embedded in cement would control the local growth of a tumour. In 15 rabbits we injected 0.1 ml of VX2 tumour suspension into the proximal tibia. At 3, 5, 7, 10 and 14 days three animals were killed and the tibiae removed and examined histologically. With increasing growth of the VX2 carcinoma there was increased bone destruction and a rise in the numbers of osteoclasts, but after 14 days the numbers of osteoclasts had decreased. We then injected VX2 into the tibiae of another 45 rabbits. After 5 days most of the tumour was curetted out and the defect filled with cement containing either 0 g, 0.1 g, 0.5 g, 1.0 g or 2.0 g MTX/40 g cement. The rabbits were divided into three groups and killed at 3, 7 or 10 days after implantation of cement. The number of osteoclasts and the amount of bone destruction were measured in each tibia. In all three groups bone destruction and osteoclast proliferation were markedly decreased with higher doses of MTX, but bone destruction was not eliminated. Our findings show that in the higher doses used, which were not toxic to the animal, MTX-embedded cement may be of value in minimising the amount of tumour-induced osteolysis and may be a useful adjunct in the surgical management of pathological fractures.

Animals↗

PubMed1995

Short-chain fatty acids modulate growth of lactobacilli in mixed culture fermentations with propionibacteria.

Three strains of Lactobacillus (L. helveticus ATCC 15009 and CRL 581, and L casei LC 3) were paired with three strains of Propionibacterium (P. freudenreichii AP8, P. freudenreichii GP6 and P. acidipropionici CRL 756) and grown in individual and mixed cultures in a complex medium. Bacterial growth, carbohydrate consumption, and production of acids was determined and compared after mono and binary culture. Propionibacterium strains were inhibited in mixed cultures that rapidly reached low pH values, and stimulated in those with slow pH reduction. In several pairs Lactobacillus strains were stimulated by mixed cultivation, while in others they were unaffected or inhibited. Lactic acid reduction by Propionibacterium consumption was not always enough to produce a stimulatory effect on growth of lactobacilli. The behaviour of Lactobacillus strains in individual cultures in media with propionic acid was similar to that of mixed cultures with Propionibacterium. As propionic acid concentration increased in the medium and glucose was consumed, both individual and mixed cultures of lactobacilli showed inhibition of the growth and increase of the fermentation activity.

Fermentation↗

PubMed1995

Six3, a murine homologue of the sine oculis gene, demarcates the most anterior border of the developing neural plate and is expressed during eye development.

The Drosophila sine oculis homeobox-containing gene is known to play an essential role in controlling the initial events of pattern formation in the eye disc and is also required for the development of other parts of the fly visual system including the optic lobes. In this paper, we report the isolation of a sequence-related gene referred to as Six3. Based on its amino acid sequence, this gene can be included in the new Six/sine oculis subclass of homeobox genes. Early on, Six3 expression is restricted to the anterior neural plate including areas that later will give rise to ectodermal and neural derivatives. Later, once the longitudinal axis of the brain bends, Six3 mRNA is also found in structures derived from the anterior neural plate: ectoderm of nasal cavity, olfactory placode and Rathke's pouch, and also the ventral forebrain including the region of the optic recess, hypothalamus and optic vesicles. Based on this expression pattern, we conclude that Six3 is one of the most anterior homeobox gene reported to date. The high sequence similarity of Six3 with the Drosophila sine oculis, and its expression during eye development, suggests that this gene is the likely murine homologue. This finding supports the idea that mammals and insects share control genes such as eyeless/Pax6 (Halder, G., Callaerts, P. and Gehring, W. J. (1995) Science 267, 1788-1792), and also possibly other members of the regulatory cascade required for eye morphogenesis. In Small eye (Pax6) mouse mutants Six3 expression is not affected. Finally, based on the chromosomal localization and the expression pattern of the mouse Six3 gene, the human Six3 cognate could be a good candidate to be at least one of the genes affected in patients with holoprosencephaly type 2 due to an interstitial deletion of 2p21-p22. This region shares a homology with the distal region of mouse chromosome 17 where Six3 has been mapped.

Amino Acid Sequence↗

PubMed1995

Homeobox genes and connective tissue patterning.

In vertebrates, limb tendons are derived from cells that migrate from the lateral plate mesoderm during early development. While some of the developmental steps leading to the formation of these tissues are known, little is known about the molecular mechanisms controlling them. We have identified two murine homeobox-containing genes, Six 1 and Six 2, which are expressed in a complementary fashion during the development of limb tendons. Transcripts for both genes are found in different sets of phalangeal tendons. Six 1 and Six 2 also are expressed in skeletal and smooth muscle, respectively. These genes may participate in the patterning of the distal tendons of the limb phalanges by setting positional values along the limb axes.

Amino Acid Sequence↗

PubMed1995

Methotrexate loaded acrylic cement in the management of skeletal metastases. Biomechanical, biological, and systemic effect.

Skeletal metastases occur commonly, and frequently are complicated by the development of an impending or pathologic fracture. In the majority of instances, these patients are best treated by internal stabilization, frequently supplemented by methylmethacrylate, to relieve pain and maintain the patient's mobility. The underlying tumor may continue to grow, and if this occurs the progressive lysis may result in loosening and subsequent failure of the implant. To prevent additional local growth, postoperative radiotherapy is recommended, and many patients also receive endocrine or chemotherapy, but the adjuvant therapy is not always successful in preventing progressive local tumor induced osteolysis. It is possible that the addition of chemotherapeutic agents to the methylmethacrylate may inhibit local growth. This study was performed to determine the biomechanical, biologic, and systemic effects of adding methotrexate to methylmethacrylate. The results show that the addition of methotrexate in as much as a concentration of 2 g methotrexate per 40 g cement did not significantly alter the biomechanical characteristics of the bone cement. The incorporated methotrexate was released continuously from the loaded bone cement, and in the amount and concentration used did not have any toxic effects on the host animal. The methotrexate did not appear to be affected by the heat of polymerization and had a significant systemic effect. There was a significant reduction in pulmonary metastases with methotrexate loaded cement as compared with unloaded cement, the effect being dependent on the concentration of methotrexate in the cement. The results of these studies indicate that methotrexate loaded cement may have an important role to play as part of the orthopaedic management of impending and pathologic fractures.

Animals↗

PubMed1995

[Lactose digestion by milk fermented with Lactobacillus acidophilus and Lactobacillus casei of human origin].

The aim of the present study was to determine whether a fermented milk containing Lactobacillus casei and Lactobacillus acidophilus strains isolated from human subjects (CFM) and developed by CERELA (Centro de referencia para Lactobacilos) is better tolerated than regular milk (RM) by subjects with lactase deficiency (< 1 unidad) and lactose intolerance. We studied the digestion of the lactose present in the two milk preparations which were administered to 18 healthy subjects with lactase deficiency and 12 control subjects. Each subject ingested in random sequence on different days, 480 ml CFM, 480 ml RM and 240 ml CFM and 240 ml RM. Breath hydrogen (H2) test was used to measure lactose absorption and orocecal transit time (OCTT). The peak H2 ppm results after 480 ml of CFM were ingested, reached 19.5 +/- 12.1 ppm. The same reading when 480 ml of RM were ingested was 52.6 +/- 31.9 ppm (p < 0.008). The results also showed that 480 ml of CFM delayed OCTT median 111.0 +/- 6.78 min versus 54.0 +/- 5.09 min of RM (p < 0.001) and reduced the development of symptoms (p < 0.08) such as bloating (p < 0.05), borborygmi (p < 0.025) diarrhea (p < 0.05) and abdominal colics (p < 0.05). In spite of the small number of cases studied, it seems justified to conclude that CERELA fermented milk significantly influences lactose digestion and minor development of symptoms in lactase-deficient subjects and lengthens significantly the orocecal transit time compared with regular milk.

Adult↗

PubMed1994

Biotherapeutic role of fermented milk.

Fermented milk was used as therapy in infantile diarrhoea due to post-gastroenteritis syndrome. This treatment eliminated the disease in 4.0 days (mean value, SD = 2.8; n = 13) and allowed patients to return to free feeding according to their age. The weight percentile variation during treatment with fermented milk (15 days) was higher in the patients showing 3rd degree malnutrition than in other children. Bacteriotherapy can restore faecal flora which has been lowered by diarrhoea. Our results showed that levels higher than 10(6) UFC lactobacilli/g of faeces correlated with a healthy status of the children. Clinical applications of fermented milk with a mixture of Lactobacillus casei and Lactobacillus acidophilus in the prevention of gastrointestinal disorders are possible.

Animals↗

PubMed1994

Medical art in the courtroom.

An anecdotal account of the experiences of a freelance medical artist in providing artwork for litigation. The requirements for presentation of artwork in court are discussed, and some practical problems addressed. Two examples are shown of cases illustrated for use in court.

Atlanto-Axial Joint↗