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Biomedical subjects

R M Guedes

Publications and source records attributed to R M Guedes.

5 recordsLinked to original sources
PubMed2004

Viscoelastic behaviour and failure of bovine cancellous bone under constant strain rate.

A programme has been established to characterize the long-term behaviour of cancellous bone. Fresh bovine cancellous specimens of dimensions 10 x 10 x 10 mm3 and 10 x 40 x 3.6 mm3 were manufactured and used within the testing programme. Results published in the literature indicate that the long-term behaviour of cancellous bone is well described by a power law, which is a very similar response of typical polymers. So far, dynamic mechanical tests (DMA) in three-point bending, under frequencies between 0.01 and 100 Hz at room temperature, confirmed the published results in a qualitative way. Nevertheless, the measured dimensionless damping, tan delta, was slightly higher than the values reported in the literature for the compact bone. The relaxation curves were obtained from dynamic tests and confirmed that bone relaxation modulus can be described by a power law function of time. Tests under constant compression strain rate were performed at four different strain rates: 0.15/s, 0.015/s, 0.0015/s and 0.00015/s and strain rate dependent behaviour was observed. An average elastic bending modulus of 300 MPa was obtained.

Animals↗
PubMed2001

The influence of parity order and body condition and serum hormones on weaning-to-estrus interval of sows.

This study was performed to investigate the weaning-to-estrus interval (WEI) in primiparous and multiparous sows in relation to their weight and back-fat thickness changes and serum hormone imbalance (insulin, growth hormone, and cortisol) at the end of gestation and during lactation. Ten primiparous and ten multiparous Camborough sows, fourth to seventh parity, were used in this experiment. During gestation, daily food intake was 2.4 kg (sow commercial diet: 2.96 Mcal/kg, 16% crude protein) and during lactation all sows were fed on a wet commercial diet (3.34 Mcal/kg, 17% crude protein) ad libitum, three times per day. Blood samples were collected and back-fat thickness at the P(2) site were recorded at 6 days before and 2, 7, 14, 21 and 25 days after farrowing. Body weight was recorded on the same dates, except the date before farrowing. The WEI was also recorded. The average daily feed intake was different (P<0.05) between primiparous and multiparous sows during lactation (5.23 versus 5.72kg per day, respectively). There was a difference (P<0.05) between primiparous and multiparous sows in total percentage of back-fat thickness loss from the end of gestation until weaning (-20.18 and -9.03%, respectively). The total percentage of weight loss during lactation was slightly greater (P>0.05) in multiparous than primiparous sows. Weaning-to-estrus interval was greater (P<0.05) in the primiparous group when compared with the multiparous group (5.55 and 4.22 days, respectively). No differences were found in insulin, growth hormone (GH), and cortisol concentrations between parity groups, except on the 21st day of lactation, when GH was greater in primiparous sows. There was no correlation between percentage of total weight loss and WEI, or percentage of back-fat thickness loss (total or by periods) and WEI. There were positive correlations between GH serum concentration on the 14th and 21st days and the percentage of weight loss in the third week of lactation (r=0.46, P<0.04 and r=0.52, P<0.02, respectively), and between GH concentration on the 21st and on weaning days and WEI (r=0.54, P<0.02 and r=0.42, P<0.06, respectively). Our results indicate that the hormone change (imbalance) during lactation, mainly GH, seems to be a better parameter to explain the difference in WEI between primiparous and multiparous sows than change in body condition.

Adipose Tissue↗
PubMed1999

Detection of BHV-1 in a naturally infected bovine fetus by a nested PCR assay.

Bovine herpesvirus 1 (BHV-1) is frequently associated with abortion in naturally and experimentally infected cattle. Most of the virus isolation and immunofluorescent antibody protocols described in the literature for detecting BHV-1 in bovine foetuses are rather laborious, costly and time-consuming. The detection is described of BHV-1 in the tissues of a naturally aborted bovine foetus by a nested PCR assay with no further hybridization procedures. Optimal results were achieved by filtering the foetal tissues on a chromatography column before DNA extraction, by using two pairs of primers in a nested PCR and by evaluating the amplification products on silver-stained polyacrylamide gels. This nested PCR was faster and easier to perform than the virus isolation test. To our knowledge, this is the first time that BHV-1 has been detected in the tissues of a naturally infected bovine foetus by means of a nested PCR. The test seems to be a practical alternative for rapid detection of BHV-1 in bovine foetus.

Abortion, Veterinary↗
PubMed1995

Frequency of cholelithiasis in alcoholics.

In order to determine the frequency of biliary lithiasis in alcoholic patients without signs of hepatic cirrhosis, we submitted 106 male alcoholics (mean age, 42.2 +/- 11.2 years) to ultrasound examination of the biliary system. Cholelithiasis was present in 6 (5.6%). We did not observe any association between the quantity of ethanol consumed and/or the time of consumption and the presence of cholelithiasis. There was no significant difference between the frequency of cholelithiasis in these patients and that found in autopsies carried out on 716 male patients (6%) at the Hospital de Clínicas, Universidade Federal de Uberlândia, during the period 1982 to 1993. Thus, we conclude that in the cases we examined, alcoholism did not represent a risk factor for biliary lithogenesis.

Adult↗