PubMed Health⌕ Search

Biomedical subjects

W Becker

Publications and source records attributed to W Becker.

At least 91 records · Page 5Linked to original sources
PubMed1991

Embryonic development of the shell in biomphalaria glabrata (Say).

During embryogenesis of the fresh water snail Biomphalaria glabrata (Say) (Pulmonata, Basommatophora) shell formation has been studied by light and electron microscopical techniques. The shell field invagination (SFI), the secretion of the first shell layers, the development of the shell-forming mantle edge gland and spindle formation have been investigated. During embryonic development at 28 degrees C environmental temperature, the shell field invaginates after 35 h. After 40 h the SFI is closed apically by cellular protrusions and scale-like precursors of the periostracum. The first electron translucent layer of the periostracum stems from electron dense vesicles of the cells which lie at the opening of the SFI. A second electron dense layer appears some hours afterwards. When the shell appears birefringent in the polarizing microscope (45 h of development) calcium can be detected in it using energy dispersive x-ray analysis. As calcification occurs the intercrystalline matrix appears under the periostracum and the SFI begins to open. In embryos of 60 h the mantle cavity appears at the left caudal side. When the mantle edge groove develops (65 h of development) lamellate units are added to the outer layer of the periostracum, but no distinct lamellar layer is formed in B. glabrata. In addition to the lamellar cell and the periostracum cell, a secretory cell can be observed in the developing groove. After 65 h of development, spindle formation starts and the shell begins to coil in a left hand spiral. After 5 days of development the embryos are ready to leave the egg capsules.

Animals↗
PubMed1991

[Distribution of bromo[methylene-3H]acetamide in Oncomelania snails, carps, and mice].

Bromoacetamide show a high molluscicidal effect, low toxicity to fish and good solubility in water. It is a promising molluscicide. The present paper reported the distribution of bromo[methylene-3H]acetamide in Oncomelania snails, carps, and mice. Radioactivity in animals was measured by liquid scintillation counting. In Oncomelania snails the radioactivity gradually increased with exposure time and drug concentration. The highest level was found in the head-foot, reaching 12.5 x 10(3) dpm.mg-1 after exposure to the drug for 24 h, whereas the levels in liver and other tissue were 3.0 x 10(3) and 3.8 x 10(3) dpm.mg-1 respectively. Carps absorbed bromo[methylene-3H] acetamide similarly as in Oncomelania snails, but the levels in tissues were less than those in Oncomelania snails. Bromo[methylene-3H]acetamide 0.5 ml (1.4 mumol.L-1) was given ig to mice. Blood samples of 3 mice were collected at 0.5, 1, 3, 6, 12, 24 and 96 h after ig. The peak levels was found within 12 h and then declined gradually.

Acetamides↗
PubMed1991

99mTc-labelled anti NCA-95 antibodies in prosthetic heart valve endocarditis.

A 54-y old women with earlier replacement of the mitral and aortic valves and clinical signs of localized endocarditis was studied with 99mTc-labelled anti NCA-95 antibody. Whereas echocardiographic findings were negative, increased radionuclide uptake was observed left parasternal over the mitral valve as a sign of prosthetic valve endocarditis. This result could be confirmed by a similar study with leukocytes labelled in vitro with 111In-oxine.

Antibodies, Monoclonal↗
PubMed1991

Principles and techniques of guided tissue regeneration.

Guided tissue regeneration is an accepted technique to promote new attachment in periodontal therapy. It is supported by sound basic research indicating that the definitive factor in the obtainment of regeneration is the source from which the cells repopulating the exposed root surface originate. These studies have indicated that cells proliferating from the periodontal ligament have the greatest potential for achieving new attachment. The use of barriers during periodontal surgery permits the possibility of periodontal ligament proliferation toward the exposed root at the same time that epithelial and gingival connective tissue proliferation is blocked. Studies in which Gore-Tex periodontal material has been used as a barrier have shown positive results in animal and clinical studies. Histologically, the formation of new cementum, bone, and periodontal ligament has been demonstrated. Clinically, beneficial results have been documented in the treatment of intrabony defects with three-wall, two- to three-wall, or funnel-shaped topography. Also, Class II furcations with or without a vertical component have been treated successfully by guided tissue regeneration.

Animals↗
PubMed1991

Biokinetics and estimation of dose from 99mTc-labelled polyclonal human immunoglobulin (HIG).

Recently, polyclonal unspecific human immunoglobulin was suggested as a new agent for the localization of inflammatory lesions. Little information about the biodistribution of this radiopharmaceutical was reported so far. To obtain further information, 99mTc-labelled human immunoglobulin (HIG) was administered to a volunteer with presumed normal biokinetics. The absorbed doses to the organs were calculated according to the MIRD concept. The scintigraphic images at 1, 2, 4 and 24 h post injection demonstrated a prolonged activity retention in the blood and high activity in the kidneys, bladder and also in the liver. No significant uptake in the bowels and the marrow could be observed over the whole period of study. 27.4% of the administered activity was excreted in the urine within 24 h. The calculated organ absorbed doses, all in microGy/MBq, were estimated as follows: whole body 2.7, liver 7.3, spleen 12.0, kidneys 15.3, lungs 3.2, marrow 9.6 and gonads 17.0. From these results an effective dose equivalent of 7.9 x 10(-3) mSv/MBq was calculated. The cancer risk estimate of 5 x 10(-5), using 370 MBq 99mTc-HIG, may be considered quite low in comparison to other scintigraphic methods of diagnosing inflammation.

Abdomen↗
PubMed1990

Comparative glucose tolerance studies in the freshwater snail Biomphalaria glabrata: influence of starvation and infection with the trematode Schistosoma mansoni.

The dynamic reactions of B. glabrata on intravasal loads of 20-1000 micrograms glucose.g live fresh wt-1 were studied in standard fed snails (SFS). Starved snails (SS) and snails infected with S. mansoni (IS) were given 100-500 micrograms glucose.g fresh live wt-1. Mean hemolymph glucose level was 12.1 mg.100 ml-1 in SFS. It was not significantly lower in SS (10.7 mg.100 ml-1), but significantly reduced in IS (8.5 mg.100 ml-1). Since hemolymph volumes were significantly increased in SS, the amount of circulating glucose (pool) did not change (75 micrograms.g body weight-1) compared to SFS (62 micrograms.g-1). It was, however, reduced to 41 micrograms.g-1 in IS. In SFS the circulating glucose pool had to be doubled to induce significantly elimination of the injected glucose. Tripled pools were eliminated with half-times of 45 min, whereas lower and higher glucose loads were eliminated significantly slower (half-times: 80-105 min). Glucose tolerance of SS was reduced: half-times were doubled, and metabolization of injected glucose was reduced. Since tissue fresh weights were lowered by 40%, absolute incorporation of 14C from labeled glucose was lowered, but specific incorporation (per mg) was higher than in SFS and IS. Glucose tolerance of IS was increased: metabolic clearance rates rose by 70% and half-times were shortened by 30%, though absolute and specific rates of 14C incorporation were lowered. However, IS lost 25% of the label to the water, whereas SFS lost 12% and SS only lost 8%. Using the antimetabolite 2-deoxyglucose, 80% of the losses proved to be glucose in IS, and 50% in SFS. The present results suggest the existence of a glucostatic regulation in B. glabrata with lower sensitivity and capacity than in mammals. As to glucose tolerance, the often reported parallelism in metabolic shifts induced by starvation and parasitic infection was not confirmed.

Animals↗
PubMed1990

Imaging rheumatoid arthritis specifically with technetium 99m CD4-specific (T-helper lymphocytes) antibodies.

CD4 expressing T-lymphocytes are involved in the pathogenesis of rheumatoid arthritis, so the possibility of using radiolabelled CD4-specific antibodies to localise diseased joints was studied. Prospectively six patients with rheumatoid arthritis were investigated. Five of them received 200-300 micrograms of a 555 MBq technetium 99m CD4-specific antibody (MAX.16H5) and were examined with three phase bone scans. Max.16H5 (IgG1) was labelled according to the mercaptoethanol (Schwarz) method. Lymphocytes of one patient were isolated on a Ficoll-Hypaque gradient and labelled with the antibody in vitro. Scans were performed 1.5 h, 4 and 24 h post injection in anterior and posterior views. In all patients, diseased joints could be clearly imaged at as early as 1.5 h. The localisation of the diseased joints correlated (P less than 0.01) with the clinical signs, with the early methylene diphosphonate (MDP) scan (P less than 0.01) and only weakly with the late bone scan (P greater than 0.05). According to these data we conclude that 99mTc-labelled CD4-specific antibodies specifically image actively diseased joints in rheumatoid arthritis.

Antibodies, Monoclonal↗
PubMed1990

Bone scan and red blood cell scan in a patient with epidermal naevus syndrome.

A bone scan and red blood cell scan in the rare epidermal naevus syndrome, associated with multiple haemangiomas of the bone and hypophosphataemic osteomalacia in a 20-year-old man are reported. The typical pattern of osteomalacia on the bone scan was associated with lesions of increased bone metabolism in the peripheral bones. The haemangiomas did not pool labelled red blood cells. Thus, the bone scan seems to be suitable for diagnosing the complete extent of haemangiomas in bone, but they could not be specifically proven by red blood cell pooling.

Adult↗