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Biomedical subjects

B Becker

Publications and source records attributed to B Becker.

At least 91 records · Page 5Linked to original sources
PubMed1982

Ocular and systemic effects of acetazolamide in nephrectomized rabbits.

The effects of acetazolamide on intraocular pressure (IOP) were studied on rabbits previously nephrectomized to eliminate the renal effects of the drug. Administration of acetazolamide (5 mg/kg i.v.) reduced IOP from a baseline of 15.2 to 12.2 mm Hg 2 hr later. This dose was found not to alter arterial blood pH, pCO2, bicarbonate, or base excess. However, 4 hr after drug administration anterior chamber aqueous humor showed significant reductions in bicarbonate, pH, and base excess, whereas aqueous humor ascorbate was significantly elevated. Administration of acetazolamide 15 to 50 mg/kg i.v.) to nephrectomized rabbits caused significant acidosis and pCO2 retention, presumably related to red blood cell carbonic anhydrase inhibition. IOP reduction at these higher doses was greater than that which followed the 5 mg/kg administration.

Acetazolamide↗
PubMed1982

[The differential diagnosis of the unilateral by hyperlucent lung. Two case reports (author's transl)].

The "unilateral hyperlucent lung" is a roentgenologic diagnosis based on an increased radiolucency of one lung. Aetiology and pathogenesis of this clinical syndrome are discussed together with two own case reports about a 9-year-old girl and a 3-month old boy. Anamnesis, bronchography, scintigraphy and angiocardiography in the girl revealed a Swyer-James syndrome, where typically only one lung is damaged by obliterating bronchiolitis. In the patient the pulmonary changes developed subsequently to a measles-pneumonia, possibly enhanced by an additional pollinosis. The 3-month old infant had a left-sided pulmonary artery hypoplasia and obstructive bronchitis in both lungs. Up to its 7th month of life the child developed sufficiently under conservative therapy, but then a life threatening pneumonia with obstructive bronchitis and respiratory failure occurred, 3 weeks of artificial respiration were without success. The subsequent pneumectomy revealed a hypoplasia of the left lung and a big tracheal cyst as cause of the severe obstruction.

Age Factors↗
PubMed1981

One-hour intraocular pressure response to timolol. Lack of correlation with long-term response.

The initial topical administration of 1 drop of 0.25% timolol maleate in 25 nontreated ocular hypertensive patients resulted in a significant reduction of mean intraocular pressure one hour later, from a baseline of 28.1 +/- 5.3 (mean +/- SD) mm Hg to 18.5 +/- 4.5 mm Hg. Two patients (8%) failed to show at least a 10% decreases in IOP one hour after the initial administration. After three to four weeks of twice a day unilateral therapy with 0.25% timolol, mean IOP increased to 21.1 +/- 4.2 mm Hg. At this time seven patients (28%) failed to obtain a 10% decrease in IOP from topical timolol administration. Changing to 0.5% timolol for three to four weeks did not cause an additional significant lowering of IOP (20.4 +/- 3.5 mm Hg). At this time five patients (20%) had less than a 10% reduction in IOP. The one-hour response failed to predict future IOP nonresponsiveness.

Administration, Topical↗
PubMed1981

On the nature of the proglottids of cestodes: a light and electron microscopic study on Taenia, Hymenolepis, and Echinococcus.

The organisation of five species of cyclophyllidean cestodes (Hymenolepis nana, H. diminuta, H. microstoma, Taenia (Hydatigera) taeniaeformis, Echinococcus multilocularis) has been studied using light and electron microscopy (SEM, TEM). It was found that there is no indication of any internal structure separating the proglottids, which are recognisable superficially. Thus in cestodes there is no metameric segmentation as in annelids. The implications of these findings on the terminology of tapeworm morphology are critically discussed.

Animals↗
PubMed1981

Ultrastructural investigations on the effect of praziquantel on the tegument of five species of cestodes.

Adult Hymenolepis diminuta, H. microstoma, H. nana, Echinococcus multilocularis, and Taenia (Hydatigera) taeniaeformis have been exposed in vitro in media containing 0.1 to 100 micrograms praziquantel/ml. Already after 5 min characteristic tegumental lesions, that were restricted to the growth zone of the neck region, were recognized using both scanning and transmission electron microscopy. Within the tegument numerous vacuoles were formed that released their contents to the exterior and finally caused destruction of the tegument. Proglottides of the central or posterior strobilar portions were never damaged. Larvae of T. taeniaeformis (cysticerci) and E. multilocularis (alveolar cysts) were studied employing the same methods both after in vitro exposure to and after in vivo treatment of their hosts with praziquantel. Strobilocerci of T. taeniaeformis developed identical tegumental lesions after contact with praziquantel whether incubated in vitro or treated in vitro. The wall of the bladder containing the larva remained unaffected. Evaginated protoscolices of E. multilocularis were damaged by in vitro contact with praziquantel while invaginated protoscolices remained intact. After in vivo exposure there were some fully developed evaginated and damaged protoscolices whereas all invaginated protoscolices and the cyst wall with its germinative layer were unaffected.

Animals↗
PubMed1981

Systemic factors in patients with low-tension glaucoma.

Nineteen patients (38 eyes) with low-tension glaucoma were compared with 53 subjects (106 eyes) with ocular hypertension. Comparable for age and sex, the 2 groups were assessed with respect to haematological and biochemical criteria, physical activity, and medical history. Statistical analyses of the differences between the 2 groups highlighted the importance of diastolic ophthalmodynamometry levels, prediagnosis exercise habits, cardiovascular disease status, and possibly systolic blood pressure. Patients with low-tension glaucoma suffered a higher prevalence of multiple abnormalities of these systemic factors than did their ocular hypertensive counterparts. There were no significant differences between the 2 groups with respect to the many other factors examined.

Adult↗
PubMed1981

Flurbiprofen and intraocular pressure.

Systemic or topical administration of corticosteroids may produce a rise in intraocular pressure (IOP). Nonsteroidal anti-inflammatory drugs (NSAI drugs) are alternate therapy for ocular inflammatory disease. Flurbiprofen, a new NSAI drug, was tested in double-masked fashion to delineate its effect on IOP. Flurbiprofen did not alter IOP in known high corticosteroid responders nor did it block corticosteroid-induced ocular hypertension.

Adult↗
PubMed1981

In vivo and in vitro experiments on the effects of praziquantel on Schistosoma mansoni. A light and electron microscopic study.

The effects of 2-cyclohexylcarbonyl-1,2,3,6,7,11b-hexahydro-4H-pyrazino[2,1-a]isoquinolin-4-one (praziquantel, EMBAY 8440, Biltricide) on Schistosoma mansoni was studied in vivo and in vitro by means of electron microscopy. It was found that 1. worms were contracted and became dislodged to the liver; 2. intensive vacuolisation occurred at distinct sites of the tegument within 5 min; 3. the surface coat remained unaffected; 4. host cells of the defense system attached to the tegumental vacuoles and started to penetrate into the interior of the parasites about 4 h after treatment; 5. only oral treatment of mice with a curative dose was lethal for the parasites, whereas worms treated with a subcurative dose recovered from the phenomena described above; 6. worms were fixed by fibroblasts to the walls of blood vessels 17 h after treatment; 7. the interior of the parasites was destroyed by host cells - especially eosinophilic granulocytes - while their exterior structures remained unchanged for some time; 8. worms disintegrated completely in the centre of typical granulomas as seen on days 14 and 18 after treatment; at this time only residues of the parasites were still recognisable within necrotic zones.

Animals↗
PubMed1981

Transport and metabolism of pyridoxine in rabbit iris--ciliary body.

Isolated rabbit iris--ciliary body preparations were found to accumulate 3H-pyridoxine by a mechanism that was time- and temperature-dependent, saturable in part, but not altered by omission of oxygen or specific ions. Tissue accumulation was only partially energy-dependent, and metabolic inhibitors had only small effects. Other B6 vitamers markedly blocked accumulation. Metabolism of 3H-pyridoxine within the tissue was extensive. After 60 min incubation with 3H-pyridoxine, about 65% of the radioactivity in the iris--ciliary body was associated with phosphorylated vitamers which did not efflux from the tissue as readily as did the nonphosphorylated forms. Unaltered pyridoxine accounted for only 16% of intracellular 3H-B6, and this did not represent accumulation against a concentration gradient. A similar saturable uptake process occurred in vivo. These data were consistent with the hypothesis that pyridoxine was accumulated by facilitated diffusion with intracellular trapping of phosphorylated metabolites.

Animals↗
PubMed1980

Timolol and epinephrine: a clinical study of ocular interactions.

In a crossover design study, we assessed effects on intraocular pressure, pupillary diamter, pulse rate, and blood pressure over six hours of one drop of 0.5% timolol maleate and 2% epinephrine hydrochloride in one eye. Both eyes of each patient had been pretreated for one week with twice-daily applications pf epinephrine or timolol, respectively. In random sequence, 20 patients (40 eyes) participated in both phases of the study. Pretreatment with timolol significantly reduced the ocular hypotensive effect of epinephrine (from 15.3% to 4.6%); epinephrine pretreatment did not affect the pressure reduction of timolol. Pretreatment with timolol enhanced the mydriatic effect of epinephrine (from 35.8% to 71.9% pupillary dilation); pretreatment with epinephrine resulted in an apparent mydriatic effect for timolol.

Aged↗
PubMed1980

Fluorophotometry and the blood-ocular barrier in experimental systemic hypertension.

Fluorophotometry was used to evaluate alterations in the blood-ocular barrier to fluorescein in rats with experimental hypertension. One hour after intravenous injection of fluorescein, 16.6 mg/kg, concentrations in the anterior chamber were increased from mean normotensive values of 135 micrograms/mL to 299 micrograms/mL (P = .005) in animals with severe hypertension. Fluorescein concentrations in the vitreous also were increased from 50 micrograms/mL in normotensive rats to 109 micrograms/mL (P = .005) in hypertensive animals. With increasing duration of systemic pressures above 160 mm Hg, anterior chamber fluorescein concentrations rose from base-line of 135 micrograms/mL to 210 micrograms/mL after one to four weeks of hypertension, and to 394 micrograms/mL after five to eight weeks (P = .005). Similarly, vitreous concentrations increased from baseline of 50 micrograms/mL to 76 micrgrams/mL and 136 micrograms/mL (P = .005) after the shorter and longer periods of hypertension. Control of hypertension with return of systolic pressure to below 120 mm Hg caused a reversal of the abnormal fluorescein permeability.

Animals↗
PubMed1980

Effect of prazosin on aqueous humor dynamics in rabbits.

Prazosin hydrochloride, a systemic antihypertensive agent, lowers intraocular pressure when applied topically to normal rabbit eyes. A 0.01% solution of topically administered prazosin did not alter out-flow facility, episcleral venous pressure, systemic blood pressure, or ocular blood flow. Tonography suggested a 27% decrease in the rate of aqueous humor formation two hours following topical administration. Posterior chamber aqueous ascorbate levels were increased following topical administration of prazosin, which also suggested a decreased entry rate of water into the eye. The effect of prazosin on IOP was prevented by systemic pretreatment with phentolamine mesylate, an alpha-adrenergic blocking agent, but not by propranolol hydrochloride or atropine sulfate. This was consistent with the known action of prazosin as a postsynaptic alpha-adrenergic blocking agent.

Administration, Topical↗