Biomedical subjects

A C Gibbs

Publications and source records attributed to A C Gibbs.

18 recordsLinked to original sources

PubMed1992

The endodontic microflora revisited.

The microbial flora of 35 dental root canals were examined, taking care to maintain the viability of obligate anaerobes which accounted for 45% of total isolations, while streptococcal species accounted for 24% of the total species isolated. Individual root canals yielded a maximum of eight bacterial species. A total of 40 different species was isolated of which the most prevalent were the facultative anaerobe Streptococcus sanguis and the obligate anaerobe, Peptostreptococcus micros (both in 23% of root canals), followed by Eubacterium aerofaciens and the 'Streptococcus milleri group' (both 17%) then Prevotella melaninogenica (formerly Bacteroides melaninogenicus), Enterococcus faecalis and Prevotella oralis (formerly Bacteroides oralis), which were each isolated from 14% of root canals. Highly significant associations were discovered between four pairs of species, viz P. melaninogenica with P. micros, P. melaninogenica with P. oralis, Prevotella corporis with Streptococcus morbillorum and Actinomyces odontolyticus with E. faecalis.

Dental Pulp Cavity↗

PubMed1991

Failure of oral zinc supplementation in atopic eczema.

An eight week double-blind placebo-controlled trial of oral zinc sulphate 185.4 mg per day was undertaken in 50 children with atopic eczema aged 1-16 years. In those receiving zinc there was no significant improvement in disease severity as assessed by surface area affected and degree of erythema, symptom scores of itch, sleep disturbance and redness of skin, or weight of emollient or topical steroid use.

Administration, Oral↗

PubMed1990

Serum levels of trace metals in children with atopic eczema.

The hypothesis that atopic eczema is associated with a non-specific decrease in the serum concentration of trace metals was examined by measurement of the levels of zinc, copper and iron in 134 children with atopic eczema and 112 controls. The results failed to confirm the hypothesis. There was no significant difference between patients and controls for the concentrations of serum zinc, iron, iron-binding capacity and albumin. Patients with eczema had a significantly higher copper concentration (median 21.0 mumol/l) than controls (median 17.0 mumol/l), and a significantly lower concentration of ferritin (median 11.9 ng/ml for patients and 16.5 ng/ml for controls). There was a highly significant correlation between the surface area of skin affected by eczema and the concentrations of albumin and orosomucoid.

Child↗

PubMed1990

Collagen in dissecting aneurysms of the human thoracic aorta. Increased collagen content and decreased collagen concentration may be predisposing factors in dissecting aneurysms.

Biochemical investigations were made into dissecting aneurysms of the thoracic aorta by taking samples at 12 specific sites from aortas of 10 patients who had dissected with fatal results in comparison with samples from 10 matched controls. When sites actually involved in dissection were compared with corresponding sites in controls, there were highly significant increases in dry weight, amount of collagen, and total protein (all p less than 0.001) and a significant decrease in collagen concentration (p = 0.016). In contrast, when samples from sites within dissected aortas, but not involved in dissection, were compared with corresponding sites in controls, there were no significant differences. We therefore conclude that in dissecting aneurysms of the thoracic aorta, there is localized expansion of the aortic matrix, due to deposition of collagen and other proteins, which decreases the concentration of matrix constituents, including collagen. Clearly, the deposition of collagen could be a cause but not a consequence of dissection. The altered composition means that the aortic wall becomes weaker and less able to withstand the mechanical stresses constantly imposed upon it.

Aged↗

PubMed1989

The improved recovery of Candida albicans from fluid culture media.

This study compares the mean generation time (MGT) and lag period of the growth of Candida albicans in four blood culture media, under a variety of conditions of incubation. The media compared were Bactec 6B, brain-heart infusion, malt extract broth and Sabourauds liquid medium. All four media were incubated under the eight possible permutations of the following conditions: 37 degrees C or 30 degrees C, vented or unvented, unshaken or constantly shaken. Then, using the incubation conditions found to be most favourable, minimum detection times for C. albicans were compared in the four media. The combination of incubation of the cultures at 37 degrees C, venting and constant-shaking, produced the fastest generation time with the minimum lag period. Of the media, Bactec 6B medium had the shortest lag period under these conditions while brain-heart infusion had the lowest MGT overall. Sabourauds liquid medium, which resulted in the most favourable combination of generation time and lag period, proved superior to the other media for the recovery of C. albicans.

Blood↗

PubMed1988

The Gemini conundrum--a problem of unpairable data: statistical comparison of ratios each derived from two separately estimated parameters.

In biological studies it may be necessary to compare ratios of two separately estimated parameters under test and control conditions. Since it is not always possible technically to obtain paired data for the two parameters, how does one take account of their variances? By extending previously described approximations in a modified t-test we present a BASIC computer program which may be used to solve this problem.

Algorithms↗

PubMed1988

Proximal femoral fractures: some determinants of outcome.

We identified 226 proximal femoral fractures prospectively in people aged over 60 years during one year in Stockport (population approximately 289,000). Our objective was to examine the association between primary treatment and outcome 6 months after the fracture using multivariate regression models. Higher haemoglobin concentrations and mental test scores on admission to hospital were associated with lower fatality within 6 months, whereas a high blood calcium-phosphate product, greater age, and an active medical problem at the time of the fracture were all associated with increased fatality. An intracapsular fracture, greater age, and a greater degree of dependency before the fracture all reduced the likelihood of regaining previous walking ability by 6 months. Good walking ability before the fracture increased the likelihood of walking well by 6 months. After adjusting for the effects of these extraneous variables there was no statistically significant association between treatment and outcome.

Aged↗

PubMed1988

Low prevalence of byssinotic symptoms in 12 flax scutching mills in Normandy, France.

The concentrations of airborne dust and bacteria were determined in 12 flax scutching mills and in two milk processing plants in Normandy, France. A total of 308 of 340 flax workers and 111 of 113 milk processors volunteered to answer a respiratory questionnaire. Personal exposure to airborne dust in the scutching mills varied from 22.2 mg/m3 to 144 mg/m3 and areal concentrations from 8.92 mg/m3 to 47.1 mg/m3. The concentration of Gram negative bacteria ranged from 3970 (colony forming units) cfu/m3 to 67,900 cfu/m3 and that of total bacteria from 12,900 cfu/m3 to more than 600,000 cfu/m3. In all, 20% of the flax scutchers were found, on the basis of the questionnaire, to suffer from persistent cough and 25% from chronic phlegm production. The corresponding figures among milk processors were 3.6% and 4.5%. Unexpectedly, only 12.5% of the scutchers appeared to suffer from byssinotic symptoms even though they were heavily exposed to airborne dust and bacteria. The low prevalence of byssinosis might be due to self selection of the workforce or a relatively low concentration of the causative agent despite high airborne contamination.

Air Microbiology↗

PubMed1987

How are the sub-unit pertussis vaccines to be evaluated?

Although an effective whooping cough vaccine has been available in the UK since the 1950s, its current association with neurotoxicity has resulted in poor uptake: as a consequence major epidemics (with significant morbidity and mortality) are still being experienced. Component (sub-unit) vaccines, which incorporate those antigens thought to be concerned with generating a protective effect, have been developed and are now available for field testing. This paper addresses how such a vaccine might be evaluated, the organization of a trial and the difficulties to be expected.

Age Factors↗

PubMed1987

A comparison of the adhesion, coaggregation and cell-surface hydrophobicity properties of fibrillar and fimbriate strains of Streptococcus salivarius.

Fibrillar and fimbriate strains of Streptococcus salivarius were compared for their ability to adhere to buccal epithelial cells and saliva-coated hydroxyapatite beads, and for their ability to coaggregate with Veillonella strains. The fibrillar Lancefield group K strains adhered statistically significantly better to both buccal epithelial cells and saliva-coated hydroxyapatite beads than the fimbriate strains, which lacked the Lancefield group K antigen. After 1 h the fibrillar strains coaggregated statistically significantly better than the fimbriate strains with V. parvula strain V1, but after 24 h, coaggregation both of fibrillar and of fimbriate strains reached approximately 90%. Freshly isolated Veillonella strains all coaggregated with the S. salivarius strains, but the percentage coaggregation varied considerably after 1 h depending on the Veillonella strain. Coaggregation was independent of the presence of Ca2+. S. salivarius strain HB-V5, a mutant of strain HB that had lost the Veillonella-binding protein, coaggregated weakly with V. parvula strain V1, but coaggregated very well with other wild-type veillonellae, suggesting the presence of an alternative mechanism for Veillonella-binding for strain HB. Fibrillar strains were, therefore, more adhesive to oral surfaces and coaggregated with veillonellae after 1 h better than the fimbriate S. salivarius strains. Both fibrillar and fimbriate strains were highly hydrophobic in the hexadecane-buffer partition assay.

Bacterial Adhesion↗

PubMed1985

The cell content and proliferative response of the rat thymus during first syngeneic and allogeneic pregnancy, and the effects of strain difference.

Two hundred female rats, 91-101 days of age, were used in this investigation which provided data on cell content and proliferative response of the thymus. The observations began in oestrous phase virgin females from two highly inbred strains AO(RT1u/AgB2) and DA(RT1a/AgB4), continued at five day intervals throughout syngeneic and allogeneic pregnancy in both strains and were completed in the immediate post-partum period. This experimental protocol permitted sequential observations throughout gestation and allowed syngeneic: allogeneic and interstrain comparisons to be made. The syngeneic: allogeneic comparisons demonstrated significant differences in the thymic proliferative responses while the AO:DA comparisons demonstrated significant differences in the thymic cell contents.

Animals↗

PubMed1979

Leucocyte ascorbate levels and postoperative deep venous thrombosis.

Forty-four general surgical patients were included in a prospective, randomized double-blind controlled trial of ascorbic acid (500 mg b.d.) or placebo for 7 days before operation. This was to test the hypothesis that vitamin C may reduce the instance of deep venous thrombosis postoperatively. Venous blood samples were taken before entering the trial, just immediately before surgery, on the day of operation and on three further occasions at 3-day intervals postoperatively for leucocyte ascorbic acid concentration (LAC). Venous thrombosis was diagnosed using the 125I-fibrinogen test and the leg scans interpreted by Roberts' criteria. There was no significant difference in the incidence of DVT between the treatment and placebo groups. In those with DVT (n = 23) the mean LAC on the day of operation was not significantly different from that in those without DVT. However, on the sixth and ninth postoperative days LAC levels were significantly lower in the DVT group. These results suggest that the administration of ascorbic acid preoperatively does not reduce the incidence of DVT, but a striking decrease in the LAC levels in the DVT patients is in keeping with the hypothesis that the initial event in the pathogenesis of DVT is adherence of leucocytes to the venous endothelium.

Ascorbic Acid↗

PubMed1979

Lymphoid response to pregnancy and pseudopregnancy in the rat.

Differences in weight, while cell density and differential white cell count of the thymus, spleen, iliac and popliteal lymph nodes of virgin, 10 days outbred pregnant, 10 days inbred pregnant, 10 days pseudopregnant, and 40 days outbred post-coitum rat were examined. Compared with virgin animals, significant weight gain occurred only in the thymus, spleen and iliac lymph nodes of the outbred group. Significant weight loss from the thymus and iliac nodes, and significant reductions in white cell density of the spleen and popliteal nodes occurred in delivered animals when compared with the virgin group. During pseudopregnancy significant weight loss occurred from the thymus, spleen and popliteal lymph nodes compared with the inbred group, and from the iliac lymph nodes compared with the virgin group. No significant differences were observed between the proportions of proliferating cells in the lymphocyte populations of the thymus, spleen, iliac and popliteal lymph nodes of the virgin group. In the outbred group the proliferating populations of all four tissues rose significantly above virgin levels, while in the inbred group only the iliac lymph nodes showed any significant rise above the virgin value. These findings are discussed in relation to the maternal immunological response to pregnancy.

Animals↗

PubMed1977

Histological discrimination of malignancy in mucinous ovarian tumours.

Eight histological features were measured quantitatively in a group of 77 ovarian mucinous carcinomas and a group of 28 benign mucinous cystomas. These were compared with the duration of survival of the patients and the clinical staging of the tumours. Using the method of discriminant function analysis it was possible to identify a group of tumours of 'borderline malignancy'. Although single histological features were inadequate indicators of prognosis a combination of three features proved fairly accurate.

Adenocarcinoma, Mucinous↗

PubMed1976

The carriage of Candida albicans in the mouths of rats treated with tetracycline briefly or for a prolonged period.

Rats given tetracycline in their drinking water for one week were orally inoculated with Candida albicans in the following week. Colonization of the mouth by the fungus resulted, whether the rats continued to receive tetracycline or not, over a period of 22 weeks. Histological changes indicative of oral candidosis were also found both in rats maintained on tetracycline throughout the experiment and in animals given the drug only initially. It is suggested that exposure to tetracycline as tested in this experiment causes a lasting reduction in the rat's ability to expel C. albicans, or an enhancement of the organism's colonizing propensities.

Animals↗

PubMed1976

The interaction of secretin and stimulants of gastric acid secretion in anaesthetized cats.

1. In fasting anaesthetized cats in which the pylorus and common bile duct were occluded, acid secretion in response to caerulein, desulphated caerulein, histamine and N methyl histamine given singly and combined with Boots secretin 4 C.H.R. u./kg hr has been studied. 2. Eight separate estimates of the calculated maximal response of acid (four acid stimulants given with and without secretin) did not differ significantly from one another. In the presence of secretin the E.D.50 of each acid stimulant was lowered. 3. Outputs of acid in response to the smallest doses of desulphated caerulein, histamine and N methyl histamine increased significantly when secretin was infused (P less than 0-05). 4. On a weight basis caerulein was 23, 474 and 95 times more potent than desulphated caerulein, histamine and N methyl histamine respectively. 5. When secretin was infused simultaneously caerulein was 8, 171 and 165 times more potent than desulphated caerulein, histamine and N methyl histamine respectively. 6. N methyl histamine was 5-6 times more potent than histamine on a weight basis when infused on its own; and 1-16 times more potent than histamine when given in the presence of secretin.

Animals↗

PubMed1975

The influence of secretin on the secretion of pepsin in response to acid stimulants in the anaesthetized cat.

Peptic secretion was studied in fasting anaesthetized cats in which the pylorus and common bile duct had been occluded to prevent the release of duodenal hormones which might stimulate or inhibit gastric secretion. Dilute acid was instilled into the stomach at intervals to aid recovery of gastric secretion and to preserve peptic activity. 2. Caerulein, histamine and N-methyl histamine did not increase the output of pepsin when given on their own. Desulphated caerulein was a weak peptic stimulant. 3. Two C.H.R. u./kg per hour secretin initiated pancreatic secretion, the volume of which increased progressively as the dose was increased by stages to 32 C.H.R. u./kg per hour. 4. Four C.H.R. u./kg per hour secretin did not increase the output of pepsin. Peptic secretion was stimulated by 8 C.H.R. u./kg per hour. A maximal output of approximately 2000 u. pepsin/15 min was obtained when 16 C.H.R. u./kg per hour was infused. 5. When each acid stimulant was infused along with 4 C.H.R. u./kg per hour secretin the output of pepsin increased significantly. The peak output, which usually occurred between 15 and 30 min after stimulation, did not exceed 1000 u. pepsin/15 min. 6. The proposed explanation for the potentiation of the peptic response when an acid stimulant is infused along with a dose of secretin, in itself below the threshold of peptic stimulation, is that each acid stimulant increases gastric mucosal blood flow, approximately doubling the effective concentration of secretin delivered to the peptic cell.

Animals↗

PubMed1975

The response of iliac lymph nodes to the fetal allograft.

It is well known that large pyroninophilic cell proliferation in regional lymphoid tissue preceds and accompanies cell-mediated immunological reactions. In the present study of lymph node responses in the pregnant rat it was found that there were no significant differences between large pyronionphilic cell counts from iliac nodes (which drain the uterus) and popliteal lymph nodes, in either virgin or delivered rats. The iliac large pyronionphilic cell count, however, rose significantly in early pregnancy, fell in late pregnancy and returned to virigin levels after delivery, whereas the popliteal large pyronionphilic cell count showed no significant change during pregnancy. It is also well established that plasma cell proliferation in regional lymphoid tissue precedes and accompanies antibody synthesis. In the present studies the plasma cell count in iliac nodes rose significantly and progressively during pregnancy, while in popliteal nodes it rose significantly only in late pregnancy. There was no significant difference between the plasma cell counts of iliac and popliteal nodes in virgin animals. In delivered animals the iliac plasma cell count was significantly greater than the popliteal count, and both were significantly greater than the corresponding virgin counts. It is concluded that the mother possesses the capacity for rejecting the conceptus, but there is some mechanism which blocks rejection.

Animals↗