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Biomedical subjects

G Lang

Publications and source records attributed to G Lang.

251 records · Page 14Linked to original sources
PubMedDate not supplied

Electron spin resonance of eumelanin from hair: photoinduced radicals in solid matrix.

KBr matrices appear to be convenient media to reveal the radicals formed on light exposure of eumelanin dispersions. The ESR signal of eumelanin dispersed at low concentration in KBr pellets is analyzed during and after irradiation at various wavelengths. Different types of radicals are observed. R'1- and R1-types of radicals are assigned, respectively, to neutral and deprotonated intrinsic phenoxy radicals of eumelanin. R'1 can be oxidized by oxygen as opposite to R1. R2- and R'2-types are formed in the indolic site. Water favours the conversion of R2, unreactive with oxygen, into R'2 which can be oxidized. R'1 and R2 result of an electron photoejection, respectively, from the phenolic and the indolic site. The R3-type radicals are associated with the band-to-band excitation of eumelanin considered as a semiorganized solid.

Electron Spin Resonance Spectroscopy↗
PubMedDate not supplied

Long-term evaluation of prosthetic mitral valves in sheep.

We have developed an in vivo model for chronic evaluation of prosthetic heart valves using juvenile domestic sheep. This report summarizes the results of a study conducted to assess a new bileaflet prosthetic valve. Nine juvenile sheep underwent mitral valve replacement using standard cardiopulmonary bypass techniques including mild hemodilution, systemic hypothermia, and cold fibrillatory arrest. The average time on cardiopulmonary bypass was 57 min. There were no surgical or anesthetic complications. Two (22%) early deaths occurred due to prosthetic annular size disproportion (1) and preexisting pneumonitis (1); postmortem examination of both implanted devices revealed normal function. The remaining seven animals (78%) remained clinically well and underwent left and right heart catheterization, angiography, and sacrifice after the 150th postoperative day. Left ventriculograms demonstrated normal valve function in all cases. The average mitral transvalvular gradient, as determined by simultaneous pulmonary capillary wedge and left ventricular and diastolic pressure, was 5.4 mm Hg. Thus we have developed a new in vivo model that provides a successful model for chronic evaluation of prosthetic valves using a sheep model. There are several features contributing to the success of our model. First, to decrease the possibility of bacteremia and seeding of the prosthesis, a single incision is used and intraoperative monitoring lines minimized. Second, we use a short cardiopulmonary bypass run (range 52-62 min), with no period of ischemia. Third, fresh sheep blood is transfused immediately following bypass to prevent anemia. Fourth, gastric decompression is used to prevent ruminal bloating, with the resulting vena caval compression that decreases blood return while on bypass.

Animals↗
PubMedDate not supplied

[Activity of the enzymes of cerebrospinal fluid and blood serum in patients with the concussion syndrome].

The activity of LDG, ACE and CE was determined in the lumbar CSF and blood serum of patients with sustained mild concussion of the brain. As compared to healthy persons the diseased demonstrated a significant rise of the LDG activity in the CSF while the mounting activity of 2 other enzymes, observed in individual instances in the CSF, lacked statistical significance. It was found that in functional upsets without any marked morphological lesions there may be encountered changes in the enzymatic activity that should be considered as a consequence of deranged metabolism.

Acetylcholinesterase↗
PubMedDate not supplied

[Bacteriophage therapy of septic complications of orthopaedic surgery (author's transl].

Seven septic cases have been treated by bacteriophage; two infections after insertion of a hip prosthesis, two septic arthritis of the knee, one osteomyelitis of the tibia, one septic non-union of the femur and one septic complication following Harrington rodding. Only specific phages were used in association with several types of surgical procedure. The technique of treatment is described. All cases were long-term infections with resistant organisms. Results were good in five, fair in one and one case was a failure. It is concluded that phage therapy may be helpful in the treatment of long-term infections.

Adult↗
PubMedDate not supplied

Microanatomy and number of nerve fibres of the lower intercostal nerves with respect to a nerve anastomosis. Donor nerve analysis. I. (IV).

A human intercostal nerve has about 10,000 myelinated nerve fibres, of which about 1000 to 2000 are motor. At about the axillary line the nervus intercostalis splits into the ramus cutaneous lateralis and a deep branch to the musculus rectus abdominis and other muscles. The ramus cutaneous lateralis consists of 2 skin branches of about 3000 nerve fibres and a muscle branch to the musculus obliquus externus of about 400 to 1100 nerve fibres. The deep branch to the musculus obliquus internus, the musculus transversus and the musculus rectus abdominis and the anterior skin consists of about 2500 to 7000 fibres of which 400 to 1700 are skin fibres. There is indication that the muscle branch to the musculus obliquus externus has about 50% motor fibres. The intercostal nerve is, as it splits after about 20 cm into 4 branches, a suitable donor of at least 2 different muscle functions and a skin sensible function for a direct nerve anastomosis. A crude model for calculating matching probabilities of motor and sensory fibres between donor and acceptor nerves is introduced. Besides the importance of having enough donor nerve fibres, it is calculated that the small amount of motor nerve fibres can be best used if muscle branches of the donor nerves are connected to muscle branches of the acceptor nerves. Because of the separation between normal laboratory animals and humans on the phylogenetic scale, differences in regeneration and plasticity are discussed.

Anastomosis, Surgical↗
PubMedDate not supplied

[Corneal endothelial proliferation in anterior synechiae: experimental and clinico-histopathological studies].

Corneal endothelial proliferation over the iris was studied on experimental anterior synechiae in rabbits up to 6 months. Clinico-pathologic studies of 102 post-keratoplasty eyes revealed that only 4 out of 51 anterior synechiae were endothelialized. In contrast all 10 leukomatous+ adhesions found in a series of 132 eyes removed after perforating corneal trauma were endothelialized. The above studies suggest that the most important factor for endothelial proliferation is the availability of suitable substrate. The rate of growth depends on growth factors present in anterior chamber.

Adult↗
PubMedDate not supplied

[Pathogenesis of secondary glaucoma in epithelial invasion].

Apart from meticulous wound closure certain amount of fibrin and fibroblastic activity are necessary to prevent epithelial ingrowth. Prostaglandin inhibitors and steroid may enhance such danger. The most frequent reason for glaucoma were peripheral anterior synechiae. Open angle glaucoma with stratified epithelium lining the trabeculum was less frequent. Glaucoma can be caused by goblet cells produced mucus blocking the trabeculum. Desquamated epithelial cells, pupillary block caused by epithelial invasion of anterior hyaloid and intense inflammatory reaction can also exceptionally induce secondary glaucoma.

Cell Division↗
PubMedDate not supplied

[Eye tumors in children. Histopathological aspects of differential diagnosis].

Ocular tumors in children, due to their biological characteristics, possess a special position in ophthalmology. Most of these tumors are today curable with early diagnosis and correct treatment. Therefore their differential diagnosis should be familiar to all pediatricians and ophthalmologists. Tumors were divided into three groups, concerning their localization (lid and orbit, epibulbar, intraocular). In each group histopathologic and clinical pictures of most important benign (hamartomas, choristomas and pseudotumors) and malignant (primary and metastatic) tumors were separately described and correlated, with special attention paid to differential diagnosis.

Child↗
PubMedDate not supplied

[Cotrel-Dubousset instrumentation in the treatment of scoliosis].

The authors describe the operative principles of the C.D. device reviewing implantable material (rods and hooks, screws and transverse system). The principles of this surgical approach (2 rods) which offers the possible distraction and contraction where necessary, are described. Good derotation is achieved and a strong and stable square support device enabling the patient to be got out of bed rapidly without any need for post-operative support. The post-operative care is extremely easy and a rapid return to school activity is possible.

Adolescent↗
PubMedDate not supplied

[Reflections concerning the radiological assessment of static flat foot in the child (author's transl)].

After a precise review of the numerous parameters studied classically in AP and lateral films of the feet under load, the authors emphasis 5 measurements which are easy to determine and which they feel to objectively cover all the deformities which may be found in the static flat foot. These are: Talo-calcaneal divergence in AP and lateral views, the angle between the calcaneum and the floor, the lateral cavitation index and, finally, the angle of the axis of the talus and of the 2nd metatarsal in AP. A score of 20 is attributed to each. A score of 0 to 20 is attributed to each of these points, with a possible total, therefore, of 100. A study of 119 cases of flat foot in the child treated surgically over a period of 6 years made it possible to draw the distinction between the severe flat foot requiring operation and with a total of less than 45 points, and flat foot requiring medical orthopaedic treatment only (more than 45), the score for the normal foot being of the order of 90 points. This radiological study also makes it possible to distinguish, amongst flat feet in children, straight flat foot with collapse of the medial arch but no valgus of the forefoot and valgus flat foot where there is pronation of the calcaneum and abduction of the forefoot. This distinction is important since it determines the choice of operation. Thus in a case of valgus flat foot Judet's so-called "horseman" operation is indicated whilst in a flat foot without valgus, transposition of the tibialis anterior is preferable. In many cases, the lesion is mixed and both surgical gestures are required.

Child↗
PubMedDate not supplied

[Single compartment Oxford knee prosthesis].

From 1988 to 1992, we implanted 30 Oxford single compartment prostheses. Follow-up was sufficient for study in 27 cases. The Oxford single compartment prosthesis is original because the height of the meniscal component varies with mobility during flexion-extension. This single compartment prosthesis requires a rigorous technique on the basis of well respected fundamental principles. The opposite femorotibial compartment must be untouched, otherwise a slight deviation of the axis may occur. Mobility must be satisfactory and the anterior cruciate ligament must not be injured. In our series, we obtained the same results as published in the literature, particularly those reported by Goodfellow who advocates its use. Results were satisfactory in 89% of the patients. There was an extraordinary improvement in pain symptomatology. There was little improvement in mobility. Overcorrection must be absolutely avoided because of the risk of destroying the opposite compartment. Besides the classical complications which include thrombophlebitis and retarded scar formation, we noted 3 luxations of the meniscus, 2 involving the medial meniscus and 1 the lateral meniscus. In 2 cases we had to change the meniscus (once under general anaesthesia) and in 1 cases had to reoperate to install a total prosthesis. The Oxford single compartment knee prosthesis is an important implant which has its place between osteotomy and a total prosthesis, when used according to rigorous technique. There is nevertheless the risk of meniscal luxation with this type of prosthesis.

Aged↗
PubMedDate not supplied

Recombinant human growth hormone in short children born small for gestational age. German Study Group.

The effects of recombinant human growth hormone (rhGH) treatment in 69 prepubertal, non-GH deficient children born small for gestational age (SGA) were evaluated over 2 years. At start of the study mean age was 5.1 years, mean bone age was 3.8 years and mean height SDS was -4.0. The children were randomly allocated to 3 groups receiving no treatment or daily subcutaneous injections of rhGH at a dose of 0.1 IU/kg body weight (group 0.1 IU) or 0.2 IU/kg body weight (group 0.2 IU). At start of the study mean height velocity SDS was -1.4 in the control group, -0.7 in group 0.1 IU and -1.4 in group 0.2 IU. After 2 years there was a significant increase in height velocity SDS in children treated with rhGH as compared to untreated children. Mean height velocity SDS after the first year of treatment was -1.2 in the control group, 2.8 in group 0.1 IU and 5.5 in group 0.2 IU. Corresponding values during the second year were -0.9, 1.6 and 2.9. A statistically significant difference was observed between the groups receiving 0.1 IU/kg/day and 0.2 IU/kg/day during the first year of treatment, whereas no difference between the treatment groups was found during the second year. Catch-up growth, i.e. a height velocity 1 SD above the mean, was achieved for 86% of group 0.1 IU and 95% of group 0.2 IU during the first year of treatment and was maintained for 65% and 79% of the patients in group 0.1 IU and 0.2 IU respectively in the second year. GH treatment was associated with a distinct acceleration of bone age. Tolerance of treatment was good. No clear trends were seen in any of the laboratory variables. In conclusion, this study shows that daily rhGH given at a dose of 0.1-0.2 IU/kg/day for 24 months is an effective and safe therapy to increase linear growth and induce catch-up growth in short SGA children.

Age Determination by Skeleton↗