Electromyographic kinesiology of the hand: muscles driving the index finger.
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Electromyography↗
Biomedical subjects
G Boivin
Publications and source records attributed to G Boivin.
Fluoride increases rat osteoblast function and population after in vivo administration but not after in vitro exposure.
The effects of fluoride on bone tissue are now well documented by in vivo histological studies performed on both human and animal bone biopsies and demonstrating an increase in osteoblast (OB) population. In order to elucidate whether the mechanism of action of fluoride on osteoblasts was direct or indirect, 14 three-week-old Sprague-Dawley rats were selected. Seven animals received 100 ppm fluoride as sodium fluoride (NaF) in drinking water for one month. The other animals, which did not receive fluoride, were considered as controls. At the end of the experiment, femurs and vertebrae were excised and osteoblastic cells were obtained after collagenase digestion separately from each animal. The osteoblastic cells derived from control and NaF-treated rats were exposed in vitro to 10(-5) M NaF. Alkaline phosphatase (AP) activity was measured, and the cellular proliferation was assessed by 3H-thymidine incorporation. Thymidine incorporation and AP activity were significantly higher in osteoblastic cells derived from NaF-treated rats than in cells obtained from control rats (p = 0.05 and p < 0.01, respectively). In contrast, the osteoblast proliferation and activity were not modified after in vitro exposure to NaF in cells derived from control and NaF-treated rats. In conclusion, the function of osteoblasts was not modified after in vitro exposure to fluoride. In contrast, given in vivo to rats for one month, fluoride has a mitogenic effect on osteoblasts and stimulates their activity. These data emphasize the hypothesis that fluoride may act either on osteoprogenitor cells or through an indirect mechanism mediated by a cofactor.
Administration, Oral↗
Clinical impact of ganciclovir-resistant cytomegalovirus infections in solid organ transplant patients.
Clinical consequences of ganciclovir resistant cytomegalovirus (CMV) infections were studied during 2 large prophylactic trials consisting of 100 days of valganciclovir or ganciclovir prophylaxis in solid organ transplant (SOT) recipients. The first one involved 301 high-risk (CMV donor seropositive/recipient seronegative) SOT recipients excluding lung transplants followed for 12 months, whereas the second one involved 80 lung transplant patients evaluated over 6 months. Among the 7 patients (4 non-lung and 3 lung transplant patients) carrying viruses with known ganciclovir-resistance [corrected] mutations in blood, adverse clinical outcome was only observed in the lung transplant recipients. Additionally, no CMV resistance mutations were observed in non-lung transplant patients receiving valganciclovir.
Antiviral Agents↗
Molecular and physiological effects of alpha-tropomyosin ablation in the mouse.
Tropomyosin (TM) is an integral component of the thin filament in muscle fibers and is involved in regulating actin-myosin interactions. TM is encoded by a family of four alternatively spliced genes that display highly conserved nucleotide and amino acid sequences. To assess the functional and developmental significance of alpha-TM, the murine alpha-TM gene was disrupted by homologous recombination. Homozygous alpha-TM null mice are embryonic lethal, dying between 8 and 11.5 days post coitum. Mice that are heterozygous for alpha-TM are viable and reproduce normally. Heterozygous knockout mouse hearts show a 50% reduction in cardiac muscle alpha-TM mRNA, with no compensatory increase in transcript levels by striated muscle beta-TM or TM-30 isoforms. Surprisingly, this reduction in alpha-TM mRNA levels in heterozygous mice is not reflected at the protein level, where normal amounts of striated muscle alpha-TM protein are produced and integrated in the myofibril. Quantification of alpha-TM mRNA bound in polysomal fractions reveals that both wild-type and heterozygous knockout animals have similar levels. These data suggest that a change in steady-state level of alpha-TM mRNA does not affect the relative amount of mRNA translated and amount of protein synthesized. Physiological analyses of myocardial and myofilament function show no differences between heterozygous alpha-TM mice and control mice. The present study suggests that translational regulation plays a major role in the control of TM expression.
Animals↗
Physical and chemical analyses of the mineral substance during the development of two experimental cutaneous calcifications in rats: topical calciphylaxis and topical calcergy.
In subcutaneous calcinoses induced in rats by topical calciphylaxis and topical calcergy, the ultrastructural aspects related to the evolution of calcified deposits were previously described. In the present study by means of X-ray diffraction, infrared spectrometry and electron spin resonance, different biophysical analyses are performed on the mineral substance deposited during development of calciphylaxis and calcergy. A rapid evolution of the calcium phosphate deposits into hydroxyapatite was noticed along the first 20 days of the calcinoses; from then, there is no important modification even at the later stages, and the characteristics of the mineral substance are mostly similar to that of bone tissue. The concentration of trace elements such as Mg2+ and Fe2+, is found higher in cutaneous calcinoses than in bone tissue.
Animals↗
[Cutaneous calcinosis induced by topical calciphylaxis in rats. I. Ultrastructural aspcts].
Skin calcification induced by topical calciphylaxis was provoked by a subcutaneous injection of iron chloride in rats previously sensitized by D.H.T. and studied by electron microscope. The evolution of the calciphylatic response can be resumed as follows: -- early appearance of numberous granules in the mitochondria of the cells of the connective tissue; their inorganic nature was revealed by microincineration and it is highly probable that they are a reserve of mineral ions; -- between the 6 hr, and the 18 hr, stages the interfibrillar matrix contained rounded vesicular structures, enclosed by a triple mambrane, which must surely be of cellular origin; they progressively incorporated more and more mineral particles which confirm their primordial role in the initial phases of mineralization; -- from the 14 hr. stage onward, mineral rodlets composed of chains of little dots appeared in the intercellular matrix and then on the collagen fibrils, probably in contact with the mucopolysaccharides; -- starting at the 24 hr, stage, the mineralization progressed without a vesicular intermediary forming increasingly dense and widespread plaques; the presence of needles of homogenous aspect indicated the appearance of a crystalline mineral deposit; an intrafibrillar mineral deposit becomes visible later. These results are compared with those obtained previously in other studies of experimental or pathological calcinosis and of mineralization of skeletal tissues.
Animals↗
Is a certain degree of osteomalacia involved in femoral neck fractures of the elderly? Histological approach to the problem and practical applications.
A study was made in Geneva of 14 patients with femoral neck fractures (7 subcapital and 7 trochanteric) to determine whether a certain degree of osteomalacia might be involved (group I). No patients with risks factors for osteomalacia were used. For ethical reasons, double tetracycline labelling was not possible and osteomalacia criteria were based on osteoid tissue values determined in a histomorphometric study directly on cancellous bone samples of the femoral head. A comparison was made with femoral head bone tissue taken from 12 patients with hip osteoarthritis at a distance from the remodelled territory (group II) and with iliac crest bone tissue taken from 6 patients with clinically and biochemically determined osteomalacia (group III). The patients were part of a larger group of subjects used for a biochemical blood study in which levels of albumin, calcium and 25 OHD3 as an index of vitamin D content were determined. Based on the data of the literature and the results obtained for group II, slight signs of osteomalacia were diagnosed for only one case (group I), although 25 OHD3 deficiency was found in more than a third of the subjects in that group as well as in some subjects of group II and in some of the aged controls. Skeletal aging must be considered not only in terms of unavoidable physiological factors but also within the context of living conditions. Hence the necessity of controlling calcium and vitamin D intake in the elderly, and of a histological examination for signs of osteomalacia in surgical specimens from patients with femoral neck fractures.
Aged↗
Achilles tendinitis associated with chondrocalcinosis.
Achilles tendinitis was observed in 3 patients with idiopathic articular chondrocalcinosis. It was associated with linear radiological calcifications which in this condition are not unusual but generally asymptomatic. Crystals presumed to be calcium pyrophosphate dihydrate (CPPD) were found in the 2 cases that were biopsied. In 2 patients the acute inflammation of the tendon subsided after several days, but in the 3rd it lasted 4 1/2 months, and resulted in a cicatricial thickening of the tendon with a progressive disappearence of the calcifications. Therefore, the development of Achilles tendinitis in an elderly patient may be an inflammatory reaction to CPPD crystal deposits.
Achilles Tendon↗
[The emergence of viruses resistant to antiviral agents: a new challenge].
Recent use of antiviral drugs and the increase in the number of viral infections in immunocompromised hosts have led to the development of viral resistance. In this paper, the author reviews the antiviral drugs on the market, the antiviral susceptibility tests and presents a review of the literature concerning infections with resistant viruses. Acyclovir-resistant herpes simplex and varicella-zoster virus, ganciclovir-resistant cytomegalovirus and zidovudine-resistant human immunodeficiency virus will be discussed.
Antiviral Agents↗