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Biomedical subjects

B Landis

Publications and source records attributed to B Landis.

18 recordsLinked to original sources
PubMed2002

Histological comparison of nasal polyposis in black African, Chinese and Caucasian patients.

We have compared the histological aspects of nasal mucosa biopsies (n = 130) obtained during bilateral polypectomy and ethmoidectomy performed in black African (n = 50), Chinese (n = 30) and Caucasian patients (n = 50) suffering from bilateral nasal polyposis (NP). The three groups of patients were matched for age and sex. The African and Chinese patients did not receive any medical treatment before endoscopic nasal surgery (ENS). All Caucasian patients were treated with corticosteroid nasal spray (400 mg/day) for 6 months. In the absence of subjective and objective clinical improvement, ENS was performed after antibiotic treatment for 10 days and prednisolone 1 mg/kg/day for 5 days. Clinical staging of the NP was graded from I to III (I = polyps limited to the middle meatus, II = polyps extending beyond the middle meatus, and III = polyps occupying the entire nasal cavity). Stage I NP was present in 22% of the Caucasians and 30% of the Chinese. Stage II was found in 58% of the Caucasians, 56% of the Chinese and 8% of the Africans. Stage III was found in 92% of the Africans, while only 20% of the Caucasians and 14% of the Chinese patients had stage III. The extent of submucosal oedema and number of mast cells were similar for the three groups of patients. A significantly greater number of eosinophils were observed in African polyps. Lymphocytes as well as plasmocytes were rare in African but abundant in polyps from both Chinese and Caucasian. Ulceration of the overlying epithelium of the polyps was observed in 20% of the African and 10% of both Chinese and Caucasians patients. We did not find any significant thickening of the basal membrane. We cannot exclude the possibility that the histological difference observed between African and Chinese polyps is related to the very common use among the Chinese population of topical intranasal treatment according to their traditional medicine practices. Since no major histological difference was found in the nasal mucosa and polyps obtained from the three groups of patients, NP in African, Chinese and Caucasian patients is very probably a similar inflammatory disease in all three ethnic groups.

Adolescent↗
PubMed1999

Use of enzyme penicillin acylase in selective amidation/amide hydrolysis to resolve ethyl 3-amino-4-pentynoate isomers.

The beta-amino acid, (S)-ethyl-3-amino-4-pentynoate, is a chiral synthon used in the synthesis of xemilofiban hydrochloride, an anti-platelet agent. A biocatalytic approach was developed to resolve (R)- and (S)-enantiomers of ethyl 3-amino-4-pentynoate in enantiomerically pure form employing the enzyme Penicillin acylase. In the acylation, phenylacetic acid was used as an acylating agent. We have shown that both the acylation and deacylation can be employed and that the activity of the enzyme Penicillin acylase can be controlled by maintaining an appropriate pH of the reaction medium.

Acylation↗
PubMed1998

A scoring system for capnogram biofeedback: preliminary findings.

Labored breathing and irregularities in the breathing pattern may be assessed by capnography; and, an abnormal capnogram wave form may often be rectified with the help of capnogram biofeedback. Clinical experience suggests this may relieve dyspnea but to what degree, for how long and for what conditions have not been determined; the issue is complex and much remains to be discovered. The more that can be learned about the various capnogram irregularities, the more effectively such information will guide us in therapy and research. To this end a 15-category capnogram disordered breathing scale (Landis CDBS) was developed to provide a measure of disordered breathing. The CDBS score is the ratio of the total number of abnormal capnogram forms to the total number of capnogram configurations in the test sample, expressed as a percentage. The total score as well as an accounting of each abnormal scoring category was tabulated for each subject. In this retrospective and preliminary study, findings of a normal comparison group were compared with capnogram data for 3 clinical groups: asthma, anxiety/panic attacks, and patients with diverse stress-related somatic symptoms. Mean CDBS scores were: a low 14% for the Normal group compared with 64% for the Asthma group; 66% for the Anxiety patients; and 47% for the Somatic group. Each group was characterized by distinctive clusters of capnogram abnormalities. As there are methodological limitations to this small group study, the findings require validation. However, as an introduction to the scoring system and because of its potential clinical value we present this paper now.

Adult↗
PubMed1998

Risk and clinical significance of developing antibodies induced by topical thrombin preparations.

OBJECTIVE: TO determine the clinical relevance, prevalence, and risk of antibody development in patients exposed to topical bovine thrombin preparations. DESIGN: A prevalence study of individuals previously exposed to topical bovine thrombin was done by screening using Western blot assay to detect antibodies against bovine thrombin preparations. SETTING: A large tertiary care center. PATIENTS: A convenience sample of 120 stored blood specimens from patients previously exposed to topical bovine thrombin was identified from hospital records. A control sample of 114 stored blood specimens from nonexposed patients was used. Case reviews for 2 exposed patients with severe bleeding complications and difficult clinical management are presented. RESULTS: Twelve of the bovine thrombin-exposed patients were found to have antibodies directed against bovine thrombin and other coagulation factors (95% CI, 4.6%-15.4%). Patients receiving multiple exposures were 8 times more likely to develop antibodies than were patients with a single exposure (P < .001). CONCLUSIONS: (1) Topical bovine thrombin is associated with formation of antibodies to coagulation factors; (2) Patients receiving multiple exposures are more likely to develop antibodies to coagulation factors; and (3) Topical bovine thrombin use may cause severe bleeding problems and should be avoided if there has been previous exposure.

Administration, Topical↗
PubMed1995

In vivo cholesterol kinetics in apolipoprotein E-deficient and control mice.

The in vivo total body cholesterol transport of homozygous apoE-deficient (-/-) and control (+/+) mice was evaluated by compartmental analysis of plasma cholesterol decay. Body cholesterol fractional catabolic rates of chow fed mutants were less (-/-, 0.17 +/- 0.02; +/+, 0.51 +/- 0.06 day-1) and body cholesterol contents greater (-/-, 68 +/- 5; +/+, 48 +/- 5 mumol) than controls. The body cholesterol expansion of the chow-fed mutant was extracellular with at least half in plasma. Cholesterol transport, i.e., the mass entering, moving through, and exiting the body each day, was similar (-/-, 6.9 +/- 0.7; +/+, 8.5 +/- 0.9 mumol/day) for homozygotes and controls on chow, and both tripled with cholesterol feeding. Differing from controls, however, mutants had considerable expansions of plasma and body cholesterol (-/-, 166 +/- 21; +/+, 59 +/- 11 mumol) with increments in peripheral tissue cholesterol contents. Cholesterol feeding increased control hepatic cholesterol without a change in plasma, whereas mutants had large increments in plasma cholesterol with no change in liver. Consistent with impaired hepatic uptake of cholesterol, mutants had much slower plasma clearance of lipoprotein cholesterol, as well as slower transfer to catabolic pools than normals. Treatment of homozygotes with lovastatin doubled both plasma cholesterol concentration and body cholesterol transport indicating the importance of apoE-dependent cell cholesterol transfer in synthetic down-regulation with this agent. These data indicate that mice lacking apoE have lower affinity hepatic uptake of plasma remnant cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Primary structure differences of human surfactant-associated proteins isolated from normal and proteinosis lung.

The primary structures of human pulmonary surfactant-associated proteins SP-A, SP-B and SP-C isolated from lung lavage of patients with alveolar proteinosis exhibit significant differences from lung surfactant proteins isolated from lungs of healthy individuals. In contrast to SP-A from normal lungs, proteinosis SP-A was shown by SDS gel electrophoresis to contain large amounts of unreducibly cross-linked beta chains. Specific primary structure modifications of SP-C and SP-B proteins were established by direct molecular weight and structural analysis, using [252Cf]plasma desorption mass spectrometry (PD/MS) as the principal method. In comparison to normal lung surfactant SP-B, proteinosis SP-B showed a significantly increased molecular weight by approx. 500 Da for the unreduced protein dimer. SP-C proteins from normal lungs were identified to possess a bis-cysteinyl-5,6-(thioester)palmitoylated structure, and to contain a frayed N-terminus resulting in two sequences of 34 and 35 amino acid residues. In contrast, SP-C from proteinosis patients was modified by (i) partial or even complete removal of palmitate residues and (ii) additional N-terminal proteolytic degradation. These results indicate the presence of pathophysiological structure modifications, which are likely to occur in the alveolar space, and may lead to a reduced surfactant function.

Amino Acid Sequence↗
PubMed1992

Plasma cholesterol transport in anhepatic rats.

The plasma appearance of newly synthesized cholesterol in anhepatic laboratory diet-fed rats was 10% of the intact rat. In intact rats this cholesterol was mainly ester in lower density lipoproteins, but for anhepatic rats it was virtually only free in high density lipoprotein. Chylomicron cholesterol ester was removed much more slowly from anhepatic than control plasma and returned primarily as free in high density lipoproteins, with the control return 10 times the anhepatic return. Lower density lipoprotein cholesterol ester transfer to an extravascular pool in anhepatic rats was less than 10% of controls. The liver was responsible for 95% of the extravascular lower density lipoprotein ester pool and only 50% of the for high density lipoprotein ester. Despite decreased anhepatic lipoprotein catabolism, the mass of both plasma low and high density lipoproteins progressively decreased indicating an even greater decrease in influx. The anhepatic fractional catabolic rate of apo A1 was similar to controls, but that of apo E was considerably less. Despite the unchanged catabolism of apo A1 and the reduced catabolism of apo E, plasma apo A1 decreased less than apo E after hepatectomy. The anhepatic data confirm the pivotal role of the liver in maintaining plasma low and high density lipoprotein cholesterol concentrations. They suggest that, in addition to its anabolic and catabolic functions, the liver also acts as a reservoir buffering changes in plasma concentration.

Animals↗
PubMed1990

N-terminal sequence determination of polypeptides and peptide mixtures by Edman degradation combined with californium-252 plasma desorption mass spectrometry.

The combination of manual Edman degradation with 252Cf plasma desorption mass spectrometry has been developed as an efficient method of polypeptide sequence determination. Results obtained with a variety of peptides and small proteins demonstrate unequivocal, two-fold sequence data, at each step from molecular weight identification of successively truncated Edman coupling and cleavage products. A rapid, greatly simplified procedure of manual Edman degradation with phenyl isothiocyanate was employed without extraction and purification steps, which was found compatible with plasma desorption mass spectrometry of low picomole amounts of peptide sample, at each cycle. Particular advantages of this combined method are the possibility of obtaining simultaneous sequence information from multicomponent peptide mixtures, such as proteolytic digests, and the direct identification of modified sequences, such as glycosylation sites. With the currently used conditions, plasma desorption mass spectrometry has been found feasible for approximately 30 sequence steps and sensitive to subnanomole amounts of proteins, with Mr up to approximately 10,000 Da.

Amino Acid Sequence↗
PubMed1989

A simplified single stage total hepatectomy in the rat with maintenance of gastrointestinal absorptive function.

A technique is described to remove the entire liver in a single stage with preservation of intestinal absorptive function. An inverted V-shape polyethylene cannula, either heparin bonded or silicon coated, was inserted into the portal vein and inferior vena cava to maintain venous return from the splanchnic and lower caval regions of the anhepatic rat. Blood glucose fell at a rate of 7 to 11 mg per hr per total plasma volume (4% body weight), usually resulting in hypoglycemia within the initial 2 hr. Euglycemia could be maintained in the first 3 hr after hepatectomy with hourly intravenous infusions of 2.5 to 5 mg per 100 gm body weight of glucose. Larger infusions of glucose (10 to 12.5 mg per hr per 100 gm body weight) were necessary for normal levels at later times. A 0.5 gm per 100 gm rat weight intestinal glucose bolus restored euglycemia for at least a 2-hr interval. Intestinal absorption of cholesterol and oleic acid was demonstrated in the anhepatic rat, although the latter was not so efficiently absorbed as in the control. The plasma cholesterol decreased with time in the anhepatic rat. Prompt increases were observed in plasma free fatty acid and glycerol concentrations after hepatectomy. Progressive increases in both direct and indirect plasma bilirubin levels were noted after hepatectomy. With appropriate maintenance of blood sugar, survival of 36 hr was observed. This procedure for single stage total hepatectomy in the rat can be performed in less than 30 min. The model is particularly useful for studies of the influence of the liver on postabsorptive metabolism.

Animals↗
PubMed1986

The relevance of glycosaminoglycan sulfates to Apo E induced lipid uptake by hepatocyte monolayers.

The binding of Apolipoprotein E supplemented triglyceride emulsions to sulfated glycosaminoglycans demonstrated specificity for the carbohydrate polymers. Glucosamine containing glycosaminoglycans with relatively less sulfate had little affinity for the Apo E emulsion whereas those with more sulfate (i.e. heparin and sulfated heparans) effectively bound the emulsion. Galactosamine containing glycosaminoglycans (chondroitin 4 sulfate and dermatan sulfate) demonstrated no binding. The Apo E induced uptake of triglyceride emulsions by hepatocytes was inhibited by highly sulfated polysaccharides (i.e. heparin, dextran sulfate) but other glycosaminoglycans which did not bind the emulsion were ineffective in this inhibition. The same sulfated compounds which inhibited the hepatocyte Apo E emulsion interaction effectively released hepatic lipase from isolated heptic perfusions. Glycosaminoglycan sulfates which did not bind the Apo E supplemented emulsions and did not inhibit hepatocyte association were ineffective in releasing lipase. A heparan mixture isolated from human liver was much less effective in inhibiting Apo E induced association of emulsions with hepatocytes, than heparin. A highly sulfated octasaccharide fraction isolated from bovine liver heparin inhibited more effectively than the human heparans but less than the heparin. Inhibition of Apo E mediated hepatocyte emulsion association was produced by a one hour exposure of the cells to either heparinase or heparanase. The heparanase was more active than the heparinase and both were effective in the presence of protease inhibitors. Enzymes hydrolyzing chondroitin sulfates and hyaluronic acid were ineffective in inhibiting the Apo E induced association. The specific binding of human low density lipoprotein to the hepatocyte was much less effected by the heparanase exposure than the Apo E mediated binding.

Animals↗
PubMed1983

Ruder syndrome. Clinical and pathologic correlation.

Ruder syndrome is an unusual varient of adrenal hyperfunction characterized clinically by debilitating osteopenia, and pathologically by bilateral micronodular adrenal hyperplasia. A unique case resembling Ruder syndrome is described in which the dominant pathologic feature was unilateral adrenal adenomatosis.

Adenoma↗
PubMed1970

Ego boundaries.

Explore the source record for details and available documents.

Body Image↗
PubMedDate not supplied

Is biofeedback effective for chronic tinnitus? An intensive study with seven subjects.

PURPOSE: This study was developed to test the hypothesis that intensive biofeedback and relaxation training may favorably affect chronic tinnitus. PATIENTS AND METHODS: Seven subjects with chronic tinnitus of moderate to severe intensity engaged in an intensive 5-month program of weekly, individual 90 minute sessions. All individuals attained a high standard of proficiency following training by a biofeedback specialist. A biofeedback unit was provided each subject for daily practice. Audiometric matching of tinnitus pitch and loudness and subjective comparisons of tinnitus loudness were conducted before and after every session. RESULT: Audiometric evaluation showed no changes in tinnitus loudness. Nevertheless, all subjects gained satisfaction from the training. Three reported substantial psychological benefits in coping with tinnitus, two described moderate improvement, and two experienced modest gains. CONCLUSIONS: These results highlight the role of psychological factors in tinnitus management and indicate that biofeedback-relaxation training may be useful therapy for coping with stresses of tinnitus.

Adult↗