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Biomedical subjects

B Becker

Publications and source records attributed to B Becker.

At least 55 records · Page 3Linked to original sources
PubMed1992

Hypothyroidism in adults with sickle cell anemia.

Persons with sickle cell anemia have several indications for transfusion of red blood cells. One of the complications of transfusion of red blood cells is iron overload. Iron overload has been associated with multiple endocrine abnormalities. We report herein three cases of hypothyroidism in adult individuals with sickle cell disease. All three patients were over the age of 45 years at the time of the diagnosis and had received multiple units of transfused red blood cells and had serum ferritin levels of greater than 6,000 ng/mL. All patients were diagnosed during times when they were critically ill. Replacement therapy was instituted in all cases; however, all three patients died shortly after the diagnosis of hypothyroidism was made. Congestive heart failure appeared to be a primary cause of death in all three patients. In the one patient in whom a postmortem examination was done, there was evident extensive fibrosis of the thyroid gland as well as extensive deposition of iron in the cells lining the thyroid follicles. We believe that this represents the first report of clinical hypothyroidism in patients with sickle cell anemia who have received multiple transfusions. Awareness of this condition is especially important given that congestive heart failure is common in sickle cell disease.

Anemia, Sickle Cell↗
PubMed1992

Psoriasis and human immunodeficiency virus infection.

BACKGROUND: Psoriasis associated with human immunodeficiency virus (HIV) infection has been reported to be severe and perhaps associated with decreased survival. OBJECTIVE: Our purpose was to document the natural history, response to therapy, and effect of psoriasis and its treatment on survival in HIV-infected patients with psoriasis. METHODS: This was an observational cohort study of 50 persons with psoriasis and HIV infection followed up during a 2-year period. RESULTS: In one third of the patients the psoriasis appeared before 1978, the year when HIV seroconversion began in San Francisco (group I). In two thirds psoriasis developed after 1978 (group II). Group I had a lower mean age of onset (19 vs 36 years) and more commonly had a family history of psoriasis. Palmoplantar and inverse psoriasis were more common in group II. Severe psoriasis occurred in one fourth of this group (12 of 50 patients). The median survival in this group after diagnosis of acquired immunodeficiency syndrome (AIDS) was 19 months, which is comparable to the median survival for all AIDS patients diagnosed in San Francisco between 1984 and 1990. CONCLUSION: Psoriasis in the setting of HIV disease may be mild, moderate, or severe. Standard therapies and zidovudine are effective in management. Survival does not seem to be adversely affected by the presence of psoriasis or its therapy.

Adolescent↗
PubMed1991

Beat-to-beat electrocardiographic morphology variation in healed myocardial infarction.

Using high-fidelity electrocardiographic (ECG) amplifiers, we measured subtle beat-to-beat ECG morphologic variations at different phases of the ECG complex. The electrocardiograms were recorded from 49 men with a documented Q-wave myocardial infarction and from 30 age-matched normal men. Forty consecutive beats were averaged to achieve an average ECG signal from which variance could be calculated. The relative variance, defined as the ratio between the integrated variance of the examined window and the integrated variance of the ECG signal that was close to full cycle length, was calculated at QRS onset and at offset in 2 frequency bands (4 to 40 and 60 to 120 Hz). Patients with healed infarction had a relative variance of 2.1 +/- 0.5 (mean +/- standard deviation [SD]) at QRS offset (a window of 40 ms), which was significantly lower than that of the healthy volunteers: 2.5 +/- 0.33 (mean +/- SD; p less than 0.02) at the low-frequency band. At the high-frequency band, patients with healed infarction had a significantly higher relative variance than the control subjects at QRS onset: 1.95 +/- 0.58 vs 1.55 +/- 0.35 (mean +/- SD; p less than 0.005). A model based on the numerous minor conduction abnormalities that exist in the chronically ischemic myocardium is presented to explain the changes in variance at the onset and offset of the QRS. The variance changes described can eventually serve as quantitative indexes of myocardial injury and electrical stability in patients with ischemic heart disease.

Aged↗
PubMed1991

Scale formation in algae.

Scale biogenesis in algae represents a unique model system to study the transport of secretory macromolecules through the Golgi apparatus (GA) and their exocytosis. The larger scales can be visualized in the light microscope, and thus the kinetics of scale assembly, transport, and secretion can be studied in vivo. In addition, scales are osmiophilic and readily visible in conventional transmission electron microscopy; thus, details of scale assembly and sorting can be studied without invoking immunolabeling techniques. The following are distinctive features of scale biogenesis in algae: 1) transport of scales through the GA-stack occurs by cisternal progression; 2) scale secretion may be very rapid (in some cases a single GA-cisterna leaves the stack every 15-20 s); 3) sorting of different scale types does not occur in the GA, but in a post-GA-compartment. Recent progress in the analysis of scale formation in the green flagellates Tetraselmis and Scherffelia is reviewed.

Animals↗
PubMed1991

Centers of rotation with transverse forces: an experimental study.

A new noninvasive method for simultaneously applying a known force system and measuring tooth movement was developed and tested. The instruments proved to be highly accurate and reliable. Using a model of an upper canine with a simulated periodontal ligament, we located the center of rotation and the center of resistance and found that the product of two distances--a, from the center of resistance to the line of application of force (F) and, b, from the center of resistance to the center of rotation (Co)--yields a constant that represents the parallel transverse forces in the same plane. Knowing this constant enables the clinician to determine the appropriate force position for a given center of rotation. We also found that the occlusoapical position of the center of resistance varies somewhat, depending on the transverse direction of loading around the long axis. Differences in values of the constant were found also to depend on the direction of loading in a given plane. Thus a transverse force exerted in a mesiodistal direction at the level of an orthodontic bracket through the long axis produces different effects from those produced when an identical force is applied in a labiolingual direction.

Computer Simulation↗
PubMed1991

Cloning and sequencing of rat plectin indicates a 466-kD polypeptide chain with a three-domain structure based on a central alpha-helical coiled coil.

We have determined the complete cDNA sequence of rat plectin from a number of well-characterized overlapping lambda gt11 clones. The 4,140-residue predicted amino acid sequence (466,481 D) is consistent with a three-domain structural model in which a long central rod domain, having mainly an alpha-helical coiled coil conformation, is flanked by globular NH2- and COOH-terminal domains. The plectin sequence has a number of repeating motifs. The rod domain has five subregions approximately 200-residues long in which there is a strong repeat in the charged amino acids at 10.4 residues that may be involved in association between plectin molecules. The globular COOH-terminal domain has a prominent six-fold tandem repeat, with each repeat having a strongly conserved central region based on nine tandem repeats of a 19-residue motif. The plectin sequence has several marked similarities to that of desmoplakin (Green, K. J., D. A. D. Parry, P. M. Steinert, M. L. A. Virata, R. M. Wagner, B. D. Angst, and L.A. Nilles. 1990. J. Biol. Chem. 265:2,603-2,612), which has a shorter coiled-coil rod domain with a similar 10.4 residue charge periodicity and a COOH-terminal globular domain with three tandem repeats homologous to the six found in plectin. The plectin sequence also has homologies to that of the bullous pemphigoid antigen. Northern blot analysis indicated that there is a significant degree of conservation of plectin genes between rat, human, and chicken and that, as shown previously at the protein level, plectin has a wide tissue distribution. There appeared to be a single rat plectin gene that gave rise to a 15-kb message. Expression of polypeptides encoded by defined fragments of plectin cDNA in E. coli has also been used to localize the epitopes of a range of monoclonal and serum antibodies. This enabled us to tentatively map a sequence involved in plectin-vimentin and plectin-lamin B interactions to a restricted region of the rod domain.

Amino Acid Sequence↗
PubMed1991

[Osteosynthesis of the clavicle. Indications, surgical technique, results].

The osteosynthesis of the clavicle should be the exception and should only be indicated in the case of complicated fractures. The high rate of pseudoarthrosis given in medical literature, is due to errors in indication, selection of implants and in surgical techniques. Procedures like intramedullar wiring, axial screwing and single cerclage-wire suture are unsuited for osteosynthesis of the clavicle. After osteosynthesis of the clavicle we have found exceptional positive results, with respect to functional, radiological and after subjective evaluation, at a low rate of complication without any consequences occurring in the years to come. These results show, that mainly good or even excellent success can be achieved, at a limited indication, combined with careful surgery and a standardized surgery procedure of osteosynthesis of the clavicle.

Adolescent↗
PubMed1990

Neurologic, computed cranial tomographic, and magnetic resonance imaging abnormalities in patients with small-cell lung cancer: further follow-up of 6- to 13-year survivors.

To determine the subsequent evolution of neurologic, neuropsychologic, and intracranial anatomic findings in long-term survivors of small-cell cancer, we repeated an evaluation done 4 years previously in patients 6 to 13 years after treatment. Fifteen patients were reevaluated with a history and physical examination, mental status examination, neuropsychologic testing, computed cranial tomographic (CCT) scans, and magnetic resonance imaging (MRI). All but one was ambulatory and none were institutionalized. Thirteen of 15 had neurologic complaints, 10 of 15 had an abnormal neurologic examination, seven of 14 had an abnormal mental status examination, 12 of 14 had abnormal neuropsychologic testing, 12 of 15 had abnormal CCT scans, and seven of 15 had white-matter abnormalities on MRI scans. No dramatic decline in performance status, functional status, neurologic symptoms, or neurologic examination occurred in these patients with 4 years of additional follow-up. More patients showed a decline in mental status examinations and neuropsychologic testing than demonstrated improvement. Anatomic studies showed no dramatic changes in the CCT scans and MRI confirmed these findings. From these data we conclude that there is a slow decline in neuropsychologic function in some of the patients surviving more than 6 years from a diagnosis of small-cell lung cancer. The anatomic abnormalities documented by CCT scans and MRI are more frequent in patients with abnormal neuropsychologic function.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Topical 8-bromo-cyclic GMP lowers intraocular pressure in rabbits.

The topical application of 8-bromo-3'-5'-cyclic guanosine monophosphate (8BrcGMP) produces significant decreases in intraocular pressure (IOP) in rabbit eyes. Maximum effects are obtained with a 4% concentration, and IOP is reduced significantly (P less than 0.001) between 30 and 240 min after administration of the agent. The decrease in IOP occurs without significant change in tonographic outflow facility. A significant further decrease in IOP can be induced by topical 8BrcGMP in rabbits whose IOP has been lowered by the systemic administration of the carbonic anhydrase inhibitor acetazolamide.

Acetazolamide↗
PubMed1990

[A new method for determination of nicotinic acid in plasma].

A new and sensitive method for the detection of nicotinic acid in plasma is described. Human or rat plasma-samples from pharmacological or pharmacokinetic studies are lyophilized and extracted with methanol. After removal of the solvent the residue is converted with N-Methyl-N-trimethylsilyltrifluoracetamide to the trimethylsilylester of nicotinic acid, separated by vpc and detected with a mass selective detector via the fragment 180 amu. 6-Methyl-nicotinic acid is used as internal standard (fragment 194 amu). With this method a detection limit of 100 ng/ml plasma is reached.

Animals↗
PubMed1989

Identification of 3-deoxy-manno-2-octulosonic acid, 3-deoxy-5-O-methyl-manno-2-octulosonic acid and 3-deoxy-lyxo-2-heptulosaric acid in the cell wall (theca) of the green alga Tetraselmis striata Butcher (Prasinophyceae).

The main constituent of the cell wall complex carbohydrate of the scaly green alga Tetraselmis striata Butcher is shown to be 3-deoxy-manno-2-octulosonic acid (42%). In addition two other 2-keto-sugar acids are present, namely, 3-deoxy-5-O-methyl-manno-2-octulosonic acid (7%), the first methylated derivative of 3-deoxy-manno-2-octulosonic acid found in nature, and 3-deoxy-lyxo-2-heptulosaric acid (11%). The characterization of the three 2-keto-sugar acids has been carried out on the corresponding methyl ester methyl glycosides using GLC-MS and 500-MHz 1H-NMR spectroscopy, and on the corresponding reduced alditol acetates using GLC-MS. Other monosaccharides occurring in the cell wall are D-galacturonic acid (14%), D-galactose (4%), D-gulose (2%), D-glucose (1%) and L-arabinose (1%).

Cell Wall↗
PubMed1989

Topical timolol administration reduces the incidence of glaucomatous damage in ocular hypertensive individuals. A randomized, double-masked, long-term clinical trial.

We conducted a randomized, double-masked, long-term clinical trial to determine whether topical timolol therapy was effective in delaying or preventing the onset of glaucomatous damage in moderate-risk ocular hypertensive subjects. In 62 patients, one eye was chosen randomly to receive timolol therapy twice daily while the fellow eye received placebo. During the course of the study, the mean +/- SD difference in intraocular pressure between the timolol-treated and the placebo-treated eyes was 2.3 +/- 2.6 mm Hg. Reproducible visual field loss developed in 4 timolol-treated eyes and 10 placebo-treated eyes. Progressive optic disc cupping was noted in 4 timolol-treated and 8 placebo-treated eyes. Using a computerized image analysis system, the mean +/- SD increase in optic disc pallor during the course of the study was 0.86% +/- 2.4% in the timolol-treated eyes as opposed to 1.80% +/- 3.6% in the placebo-treated eyes. This study provides evidence that lowering intraocular pressure by medical treatment reduces the incidence of glaucomatous damage in ocular-hypertensive individuals.

Administration, Topical↗
PubMed1989

Atrial natriuretic peptides. Effects on intraocular pressure, cGMP, and aqueous flow.

We report a significant decrease in intraocular pressure after intravitreal injection of atrial natriuretic peptide (AP). There is also an increase in cGMP in iris-ciliary body preparations after exposure to physiologic concentrations of AP in vitro. We present evidence that after intravitreal AP administration there is a decrease in aqueous humor flow associated with the decrease in intraocular pressure. The changes in aqueous humor flow were estimated by automated fluorophotometry and aqueous humor ascorbate concentrations.

Animals↗
PubMed1989

Breakdown of the blood--aqueous barrier in the rabbit eye by infrared radiation.

Breakdown of the blood-aqueous barrier was produced by infrared radiation (IR) at a heat flux from 24 to 44 J/cm2 in pigmented, but not in albino rabbits. Blood-aqueous barrier breakdown was inhibited by indomethacin and ketamine/xylazine anesthesia mixtures, but not by [D-Trp2,D-Pro7,9]-substance P. The degree of blood-aqueous barrier breakdown could be controlled by IR flux. Two models for accurate determination of the heat flux are presented.

Albinism↗
PubMed1989

Tumorigenicity testing of various cell substrates for production of biologicals.

The data presented in this paper confirm earlier findings that the antithymocyte globulin (ATG) treated newborn Wistar rat is more sensitive than the nude mouse in allowing the metastatic potential of a cell substrate to be displayed. Several human neoplastic cell lines such as HeLa, FL, Hep-2, KB and WiDr cells as well as monkey kidney cell lines such as Vero and BSC-1 cells, which failed to metastasize in nude mice, formed metastases in ATG-treated newborn rats. Earlier studies on the tumorigenicity of Vero monkey kidney cells were extended to various passage levels of BSC-1 aneuploid and CV-1 diploid monkey kidney cells in order to establish the effect of prolonged in vitro culture on the oncogenic potential of African green monkey kidney cells. It was found that BSC-1 and CV-1 cells--like Vero cells--showed increased tumorigenicity in the rat model with increasing cell passage. Cells of all three cell lines passaged 146 to 257 times formed invasive adenocarcinomas in the muscle (inoculation site) of the animals. Considering the passage levels, at which the adenocarcinomas appeared and lung metastases were detected, the malignant potential was most pronounced in CV-1 cells, followed by Vero cells and was lowest in BSC-1 cells. Results obtained from the in vitro tumorigenicity assay of cell colony formation in soft agar confirmed the rat test results: increased cell passage of all three monkey kidney cell lines resulted in higher cell colony formation. The in vitro chick embryo skin culture assay was found unsuitable for the differentiation of various passage levels of these cell lines.

Animals↗
PubMed1988

Intraocular pressure response to topical dexamethasone as a predictor for the development of primary open-angle glaucoma.

In a retrospective study we reviewed the records of 788 subjects who had been corticosteroid tested with 0.1% dexamethasone four times daily to one eye for six weeks. All subjects had normal kinetic visual fields and optic nerve heads in both eyes at the time of testing and were followed up for a minimum of five years. Some subjects had normal baseline intraocular pressures whereas others were considered to have ocular hypertension. Of 276 individuals who were high corticosteroid responders (intraocular pressure greater than 31 mm Hg during dexamethasone administration), 36 (13.0%) developed glaucomatous visual field loss during the follow-up period. Only nine of 261 individuals (3.4%) who were intermediate responders (intraocular pressure 20 to 31 mm Hg during dexamethasone administration) and none of 251 individuals who were low responders (intraocular pressure less than 20 mm Hg during dexamethasone administration) developed glaucomatous visual field loss. However, the ability of the intraocular pressure response to dexamethasone to predict the development of glaucomatous visual field loss was not as good as the predictive power of a multivariate model that included patient age, race, baseline intraocular pressure, baseline outflow facility, baseline cup/disk ratio, and systemic hypertension.

Adult↗