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Biomedical subjects

R Beck

Publications and source records attributed to R Beck.

At least 73 records · Page 4Linked to original sources
PubMed1998

Modulation of arachidonic acid release and membrane fluidity by albumin in vascular smooth muscle and endothelial cells.

Albumin is the major plasma protein circulating in blood. Albumin potently decreases capillary permeability, although the mechanisms are not understood completely. Albumin also effectively binds arachidonic acid (AA), which increases capillary permeability. To investigate the interactions of BSA and AA with the cell membrane, the effect of these substances on [3H]AA release and membrane fluidity was studied in vascular myocytes and endothelial cells. BSA (0.2 and 1 mg . mL-1) stimulated a significant release of [3H]AA from both intact rat aorta and cultured smooth muscle cells. This effect was not mimicked by gamma-globulin or myoglobin (both 1 mg . mL-1) in intact tissue. BSA, but not gamma-globulin and myoglobin, decreased the membrane fluidity (assessed as changes in the steady-state fluorescence anisotropy of 1,6-diphenyl-1,3, 5-hexatriene) in a concentration-dependent manner with a half-maximum concentration between 0.007 and 0.4 mg . mL-1 in both freshly isolated and cultured rat aortic myocytes and human umbilical vein endothelial cells. AA (1 to 200 micromol/L) caused the opposite effect, increasing membrane fluidity and antagonizing the effect of BSA. BSA modified at its arginine residues, which are thought to be important in AA binding, did not stimulate [3H]AA release and was significantly less potent than native BSA in altering the membrane fluidity. The effect of BSA can be explained by a high-affinity binding of AA to the protein and extraction of AA from the cell membrane. The interaction between BSA and AA could play a role in the regulation of vascular permeability.

Animals↗
PubMed1998

Mental health. Home alone.

Carers of people diagnosed with schizophrenia want more support and greater involvement in the care of the service user. Access to 24-hour support is highly rated. Almost half the carers in this study received no support from anyone--professional or otherwise.

Caregivers↗
PubMed1998

Resolution of severe bronchiectasis after removal of long-standing retained foreign body.

Saccular bronchiectasis secondary to the presence of a long retained foreign body is considered irreversible and an indication for resection of the diseased segment or lobe. We describe a 3 1/2 year-old girl with a retained organic foreign body for 18 months, and who was treated conservatively after laser resection and extraction of the inflammatory mass from the bronchus intermedius followed by complete resolution of the bronchiectasis. We suggest that even severe bronchiectasis following prolonged retention of a foreign body may be reversible after removal of the obstruction and reestablishment of airway patency.

Bronchi↗
PubMed1998

The forgotten condyle: Delayed hypoglossal nerve palsy caused by fracture of the occipital condyle.

Fracture of the occipital condyle is a rare injury that can be easily overlooked. Palsies of lower cranial nerves can be the only symptom of the fracture. We report a patient with isolated post-traumatic hypoglossal nerve palsy who developed hypoglossal nerve palsy within 2 months after a car accident, indicating that the acute trauma itself did not damage the hypoglossal nerve. Most likely the palsy is caused by pressure to the nerve prior to the entry or within the hypoglossal canal. Since, in the present case, the fracture was stable and the patient showed only moderate neurological deficits, the operation was deferred.

Cranial Nerve Diseases↗
PubMed1998

The natural history of infantile esotropia during the first six months of life. Pediatric Eye Disease Investigator Group.

PURPOSE: The present study addresses the natural history ocular alignment in infantile esotropia that presents at 2 to 4 months of age. METHODS: Eye alignment during the first 6 months of life was evaluated in two cohorts of healthy infants who initially had esotropia at 2 to 4 months of age; 80 infants were enrolled in a prospective study at the Retina Foundation of the Southwest (RFSW), and 41 infants were reviewed retrospectively as a pilot study for the Early Surgery for Congenital Esotropia (ESCET) multicenter trial. In addition, 79 of the 80 children in the RFSW cohort were reexamined at 4.5 years of age or older for ocular alignment and stereopsis. RESULTS: Among infants who initially had constant esotropia > or = 40 PD, 0 of 45 children in the RFSW cohort and 0 of 21 children in the ESCET cohort showed resolution to orthophoria. In addition, only 2 infants showed a reduction in angle of deviation below 40 PD (one to 35 PD and one to 20 PD). Resolution to orthophoria was noted in a few infants who initially had small angle or variable angle esotropia. On follow-up at 4.5 years of age or greater, 91% of the children in the RFSW cohort had alignment within 8 PD of orthoposition and 30% had stereoacuity of 3000" to 60". Children who underwent surgical alignment at 6 months of age had a higher prevalence of coarse stereopsis than children who underwent alignment at 7 to 15 months of age. CONCLUSIONS: Taken together, these results suggest that infants who present at 2 to 4 months of age with constant esotropia of 40 PD or greater are valid candidates for surgical treatment. In addition, data from long-term follow-up support the hypothesis that early surgical alignment may promote the development of at least coarse stereopsis in these infants.

Depth Perception↗
PubMed1998

[Corneal penetration of various aminoglycosides and quinolones].

BACKGROUND: Penetration of the aminoglycosides gentamicin and tobramycin and chinolones ciprofloxacin and ofloxacin applied as eyedrops and soaked disposable lenses (ACUVUE), used as antibiotic prophylaxis, was investigated. MATERIALS AND METHODS: 217 patients received before undergoing cataract extraction 0.3% solutions of these antibiotics as eyedrops or by soaked ACUVUE-lenses. During surgery 50-100 microliters aqueous humor was aspirated; concentration of gentamicin and tobramycin was analysed by fluorescence polarisation immuno assay, concentration of ciprofloxacin and ofloxacin was analysed by high pressure liquid chromatography. RESULTS: After application of gentamicin and ofloxacin as eyedrops and via soaked ACUVUE-lenses as drug delivery system (DDS) we found higher concentrations than after application of tobramycin and ciprofloxacin by the same modes. After using of soaked lenses as DDS the aqueous humor concentrations of all tested substances were higher than the concentrations after the frequent instillation of eyedrops. CONCLUSIONS: Penetration of gentamicin through normal human cornea is higher than penetration of tobramycin; penetration of ofloxacin through normal human cornea is higher than penetration of ciprofloxacin. The aqueous humor concentrations of ofloxacin applied as eyedrops and DDS, of ciprofloxacin and gentamicin applied as DDS allow their use as antibiotic prophylaxis in cataract surgery.

Anti-Bacterial Agents↗
PubMed1997

Cerebellar presentation of multiple system atrophy.

Early diagnosis of multiple-system atrophy (MSA) is important in patients presenting with late-onset cerebellar ataxia because it has a less favourable prognosis than other degenerative ataxic disorders. We report cerebellar presentation of MSA in a series of 16 patients, 3 of whom later developed parkinsonism. Two-thirds of them had early evidence of impaired postural reflexes with a history of recurrent falls. Some of these had a narrow-based, unsteady gait, unlike the more classic broad-based gait ataxia of cerebellar disease. On review of the patients' histories, genitourinary dysfunction (particularly impotence) was present at the onset of, or preceding, cerebellar ataxia in 60% of patients, but this had often been attributed to age, or to urological or gynaecological causes. External striated anal or urethral sphincter electromyography (EMG) demonstrated features of chronic denervation and reinnervation in 14 (93%) of 15 patients, consistent with degeneration in Onuf's nucleus as occurs in MSA. Autonomic function tests were abnormal in 9 (64%) of 14 patients. Our data suggest that close enquiry into genitourinary function and analysis of the gait disorder can be useful pointers to a diagnosis of MSA in patients with an unexplained adult-onset progressive cerebellar syndrome, and that sphincter EMG is the most useful investigation in this context.

Adult↗
PubMed1997

Hepatic microsomal enzyme induction, beta-oxidation, and cell proliferation following administration of clofibrate, gemfibrozil, or bezafibrate in the CD rat.

Male and female CD rats were administered one of two dose levels of clofibrate, gemfibrozil, or bezafibrate daily by oral gavage for a period of 14 days in order to establish an empirical data base using the Charles River CD rat with a single class of drugs against which the potency of novel proprietary compounds could be compared. Subsequent gross examination of the liver indicated significant and dose-related increases in relative and absolute liver weights in males following clofibrate and gemfibrozil. In females, absolute and relative liver weights were significantly elevated to a similar degree with either dose of gemfibrozil, and absolute liver weights were higher in clofibrate-dosed animals. Bezafibrate had no effect on female liver weights. Clofibrate and gemfibrozil increased hepatic palmitoyl CoA beta-oxidation in both sexes; however, clofibrate had the greater effect in males and gemfibrozil had the least effect in females. Bezafibrate treatment resulted in a very pronounced elevation of palmitoyl CoA beta-oxidation in the males but had no similar effect in the females. Concurrent ELISA analysis for cytochrome CYP4A revealed very good correspondence between beta-oxidation and cytochrome induction for each of the three compounds in males, but other cytochromes were not greatly affected, except CYP1A1 which was elevated in bezafibrate-dosed females. For males, further analysis for markers of cellular proliferation, namely cyclin-dependent kinases (CDK) and proliferating cell nuclear antigen (PCNA), indicated dose-related increases for both with clofibrate, increases at the high dose for gemfibrozil, and, for PCNA, a dose-related increase for bezafibrate. In females, both markers for cell proliferation showed either slight or no increases following any of the three drug treatments. These results demonstrate clear sex-dependent differences in terms of relative potency in the hepatic response of the Sprague-Dawley-derived rat to these peroxisome proliferators. Bezafibrate is most potent and gemfibrozil is least potent in stimulating peroxisome-associated beta-oxidation and cytochrome P450 4A induction in the males. Even though gemfibrozil significantly increased liver weights, beta-oxidation and cytochrome P450 4A in the females increased only after clofibrate treatment, although to a lesser degree than in the males administered the same dose. Similar sex-related differences were observed for cell proliferation. In conclusion, sex-related differences were noted in the potency to stimulate acyl Co-A oxidation, its association with hepatomegaly, and the stimulation of cell proliferation, but CYP4A induction always accompanied any substantial drug-dependent increases in beta-oxidation.

Animals↗
PubMed1997

Penetration of ciprofloxacin, norfloxacin and ofloxacin into the aqueous humours of patients by different topical application modes.

OBJECTIVE: A prospective study was undertaken to determine the transcorneal penetration of three topically applied fluoroquinolones into aqueous humour. METHODS: Two hundred and twenty-four patients undergoing cataract extraction received 0.3% ciprofloxacin, norfloxacin or ofloxacin eye drops by two different administration modes with different frequencies and intervals of application. At the beginning of cataract extraction (0.5-3 h after the last drop), 50-100 microliters aqueous fluid was aspirated from the anterior chamber and immediately stored at -80 degrees C. Antibiotic concentrations were measured using high-performance liquid chromatography. RESULTS: Generally, topical ofloxacin and ciprofloxacin yielded aqueous humour levels higher than topical norfloxacin. The highest concentrations of all tested fluoroquinolones were measured after using an application mode, in which one drop was given every 15 min between 0600 hours and 0800 hours, prior to operation. When applied by this mode, ciprofloxacin achieved a mean aqueous level of 0.380 (+/- 0.328) microgram.ml-1 (range 0.033-1.388 micrograms.ml-1), norfloxacin 0.182 (0.118) microgram.ml-1 (range 0.038-0.480 microgram.ml-1) and ofloxacin 0.564 (0.372) microgram.ml-1 (range 0.064-1.455 micrograms.ml-1). These mean concentrations were above the minimum inhibitory concentration (MIC90), concentrations required for inhibition of 90% of pathogen strains in vitro of gram-negative bacteria, such as Proteus mirabilis and Escherichia coli. Therapeutic values above the MIC90 of Staphylococcus epidermidis, the pathogen causing eye infections most frequently, were reached by 67.5% of patients after ofloxacin and by 41% after ciprofloxacin, but never after norfloxacin treatment. CONCLUSION: Of the currently available topical fluoroquinolones, ofloxacin achieved the highest aqueous humour concentration. This fluoroquinolone may be an useful ophthalmic agent for topical antibacterial management, but it does not seem to be prophylactically effective against Streptococcus pneumoniae or Pseudomanas aeruginosa.

Administration, Topical↗
PubMed1997

[Adherence of staphylococci of different hydrophobicity. Study of various intraocular lenses].

BACKGROUND: A major goal in research on intraocular lenses (IOL) is the development of new polymers and modifications to reduce foreign-body reactions after implantation. This effect may be achieved by a reduction in the surface hydrophobicity of the polymers. To illustrate the influence of surface modifications on bacterial adhesiveness, the most often isolated organism in "low-grade" postoperative endophthalmitis, Staphylococcus epidermidis, was used. MATERIALS AND METHODS: For this reason three strains of this species, the type strain ATCC 14990 and two clinical isolates (8687, 6579 I) with different hydrophobic surface properties were studied. IOL, used in the experiments were either made of PMMA or silicone with modified surfaces (unpolished, polished, heparinized). The adhesiveness of H3-thymidin-labeled bacteria was calculated/mm2 of lens surface. Each experiment was performed in triplicate and repeated three times. RESULTS: The hydrophobic-type strain showed stronger adherence to unpolished PMMA surface (8000 bacteria per mm2) compared to the polished (5200 bacteria/mm2). In contrast, the hydrophilic strain adhered with 2000 bacteria/mm2 to the unpolished and with 4200 bacteria/mm2 to the polished surface. Polishing PMMA lenses diminished the differences between the three strains. However, surface passivation of silicone lenses increased the adhesion rate of the hydrophilic strain up to 9600 bacteria/mm2. Treatment of PMMA lenses with heparin increased the adhesiveness of the hydrophilic strain and reduced the adhesion rate of the hydrophobic type strain to 250 bacteria/mm2. CONCLUSIONS: It was demonstrated that bacterial adherence to IOL also involves hydrophobic interactions. Obviously, however, that adherence reflects a complex of interactions between the two surfaces.

Bacterial Adhesion↗
PubMed1996

Effects of novel 3,4-bisphenylhex(3)enes on cell proliferation in malignant and normal cells.

The growth-inhibitory effect of several newly synthesized alkyl derivatives of 3,4-bisphenylhex(3)ene was studied in four tumor cell lines and three healthy primary cell systems. A marked inhibition of cell proliferation was noted in the neoplastic cells but not in the primary systems. No effect on the cytoplasmic or mitotic microtubule system but an increase in the gross level of 5-methylcytosine in nuclear DNA was observed. It is speculated that the selective growth inhibition of tumor cells is due to DNA-hypermethylation.

5-Methylcytosine↗