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Biomedical subjects

K Rose

Publications and source records attributed to K Rose.

At least 55 records · Page 3Linked to original sources
PubMed1998

Plasmodium falciparum polyoximes: highly immunogenic synthetic vaccines constructed by chemoselective ligation of repeat B-cell epitopes and a universal T-cell epitope of CS protein.

Effective immunoprophylaxis directed against the pre-erythrocytic stages of the malaria parasite requires a vaccine that can elicit humoral and cell mediated immunity in individuals of diverse genetic background. In order for a synthetic peptide malaria vaccine to meet these requirements, problems associated with genetic restriction, peptide chemistry, adjuvant formulation and physiochemical characterization of the final synthetic vaccine product must first be overcome. To address these issues, five polyoxime vaccine candidates have been constructed by ligating purified peptide epitopes of the P. falciparum CS protein to a branched template via oxime bonds. All five constructs, including two based on templates containing the synthetic adjuvant tripalmitoyl-S-glyceryl cysteine (Pam3Cys), were of sufficient purity for characterization by mass spectrometry. The immunogenicity of the malaria polyoximes in different murine strains was compared to that of multiple antigen peptide (MAP) constructs synthesized by standard step-wise synthesis. A tri-epitope polyoxime-Pam3Cys construct, based on the repeats and a universal T-cell epitope that contains both helper and CTL epitopes of the CS protein, was shown to be a precisely-defined synthetic malaria vaccine candidate that was highly immunogenic in murine strains of diverse H-2 haplotypes.

Adjuvants, Immunologic↗
PubMed1998

Elimination of free radionuclide by a chelating agent improves tumor-to-nontumor ratios following radioimmunotargeting with antibody labeled with 67Ga.

To circumvent radionuclide accumulation in nontarget tissues when employing metallic radionuclides for radioimmunoscintigraphy or radioimmunotherapy, we have investigated the effect of the chelating agent deferroxamine (DFO) on the biodistribution of 67Ga following its administration attached to intact monoclonal antibody MAb35 and its F(ab')2 fragment. Following administration of 67Ga-labeled MAb35, DFO accelerated whole-body elimination of 67Ga and reduced its accumulation in several normal tissues, including liver, spleen and kidney. No reduction in tumor accumulation of 67Ga was observed. Following administration of 67Ga-labeled F(ab')2 fragment, kidney accumulation was higher than with the intact antibody (29% and 4% ID/g, respectively) and blood levels lower (0.69% and 5% ID/g, respectively). Again, no alteration in tumor accumulation of 67Ga was seen following DFO, although liver, kidney and blood levels were reduced and whole-body elimination accelerated.

Animals↗
PubMed1998

Yeast meiotic mutants proficient for the induction of ectopic recombination.

A screen was designed to identify Saccharomyces cerevisiae mutants that were defective in meiosis yet proficient for meiotic ectopic recombination in the return-to-growth protocol. Seven mutants alleles were isolated; two are important for chromosome synapsis (RED1, MEK1) and five function independently of recombination (SPO14, GSG1, SPOT8/MUM2, 3, 4). Similar to the spoT8-1 mutant, mum2 deletion strains do not undergo premeiotic DNA synthesis, arrest prior to the first meiotic division and fail to sporulate. Surprisingly, although DNA replication does not occur, mum2 mutants are induced for high levels of ectopic recombination. gsg1 diploids are reduced in their ability to complete premeiotic DNA synthesis and the meiotic divisions, and a small percentage of cells produce spores. mum3 mutants sporulate poorly and the spores produced are inviable. Finally, mum4-1 mutants produce inviable spores. The meiotic/sporulation defects of gsg1, mum2, and mum3 are not relieved by spo11 or spo13 mutations, indicating that the mutant defects are not dependent on the initiation of recombination or completion of both meiotic divisions. In contrast, the spore inviability of the mum4-1 mutant is rescued by the spo13 mutation. The mum4-1 spo13 mutant undergoes a single, predominantly equational division, suggesting that MUM4 functions at or prior to the first meiotic division. Although recombination is variably affected in the gsg1 and mum mutants, we hypothesize that these mutants define genes important for aspects of meiosis not directly related to recombination.

Alleles↗
PubMed1998

Calcium- and hydroxyapatite-binding properties of glucuronic acid-rich and iduronic acid-rich glycosaminoglycans and proteoglycans.

This study describes the interaction of a small chondroitin sulphate proteoglycan and the glycosaminoglycans chondroitin 4-sulphate, dermatan sulphate and heparan sulphate with hydroxyapatite. All macromolecules possessed a high affinity, with the iduronic acid-rich dermatan sulphate and heparan sulphate displaying higher adsorption maxima than the glucuronic acid-rich chondroitin 4-sulphate. At similar concentrations, dermatan sulphate produced a 30% inhibition of hydroxyapatite-induced crystal growth, whilst chondroitin 4-sulphate yielded 50% inhibition. Estimation of the calcium binding capacity of these glycosaminoglycans using equilibrium dialysis indicated that chondroitin 4-sulphate bound five times more calcium than dermatan sulphate at a calcium concentration similar to that of serum. The data indicate a possible important role for chondroitin 4-sulphate in dentinogenesis where it is the dominant glycosaminoglycan, since it could act as a capture point for calcium ions during mineralisation, with the leucine-rich domain of its parent proteoglycan acting as anchor points to type I collagen.

Adsorption↗
PubMed1998

In vitro evidence that rabbit distal colonic muscularis mucosae has a Clostridium difficile toxin A receptor.

In the rabbit ileum Clostridium difficile toxin A causes inflammation and mucosal damage via a specific glycoprotein receptor that contains alpha-D-galactose. In rabbit colon toxin A also causes inflammation, and this is associated with increased myoelectric activity and eicosanoid production. The present in vitro study was undertaken to determine if a toxin A receptor on one or more layers of colonic smooth muscle could mediate the motor effects of this agent. Toxin A (20-100 microg/ml) was without effect on longitudinal and circular muscle but had two different effects on the muscularis mucosae. Initial exposure to the toxin caused increased numbers of spontaneous contractions and a small, atropine-, tetrodotoxin-, and indomethacin-resistant increase in resting tone. More importantly, however, 30-min exposure to toxin A resulted in attenuated muscularis mucosae responses to acetylcholine and K+. Both the small excitatory and the larger inhibitory effects of toxin A were abolished by pretreatment with the lectin BS-1, which binds to toxin A receptors, but not by the nonreceptor-binding lectin DBA. These data strongly suggest that toxin A causes significant motor effects on the distal colonic muscularis mucosae via a receptor-mediated mechanism. These mechanical data were supported by the presence of histologically demonstrable toxin A and BS-1 binding sites on the muscularis mucosae but not on either the longitudinal or circular muscle layers, both of which were unresponsive to the toxin. By depressing muscularis mucosae function and, ultimately, mucosal movement as a result of toxin A production, C. difficile may promote its own proliferation, thus further contributing to the development of antibiotic-associated colitis.

Acetylcholine↗
PubMed1998

Phase I and pharmacokinetic trial of aminopterin in patients with refractory malignancies.

PURPOSE: Aminopterin (AMT) is a potent folate analog that is no longer in routine clinical use. Because of laboratory data that suggests improved metabolism of AMT versus methotrexate (MTX) in lymphoblasts, we developed a phase I trial to determine the maximum-tolerated dose (MTD), dose-limiting toxicity (DLT), and pharmacokinetic profile of AMT. PATIENTS AND METHODS: Twenty patients with refractory malignancies were treated. The starting dose of AMT was 2.5 mg/m2 every 12 hours for two doses weekly: the dose of AMT was decreased and leucovorin (LV) rescue was added after the DLT was observed. Pharmacokinetics were performed after both intravenous (i.v.) and oral AMT administration. RESULTS: Mucosal toxicity was dose-limiting and resulted in the need for a dose reduction (dose level 2: AMT 2 mg/m2 every 12 hours for two doses weekly) and, subsequently, the addition of scheduled LV rescue (dose level 3: AMT 2 mg/m2 every 12 hours for two doses followed by LV 5 mg/m2 orally every 12 hours for two doses, starting 24 hours after the second dose of AMT). The mean areas under the curve (AUC) for the i.v. (n = 14) and oral (n = 13) doses were 1.20 +/- 0.09 (SE) and 1.05 +/- 0.14 micromol x h/L respectively. The half-life was 3.64 +/- 0.28 hours and the oral bioavailability in 12 matched subjects was 83.5% +/- 8.3%. One patient with endometrial adenocarcinoma achieved a complete response (CR) and remains on therapy at 11+ months. Seven patients had stable disease (SD) for 8 weeks or greater, which included one patient with a metastatic nerve sheath tumor who was stable for 9 months. CONCLUSION: We conclude that AMT has good oral bioavailability and that, when given on a q12 hour x two weekly schedule, the MTD is 2 mg/m2 with delayed LV rescue.

Administration, Oral↗
PubMed1998

Differential regulation of individual sulfotransferase isoforms by phenobarbital in male rat liver.

Xenobiotics that induce the cytochromes P450 also produce changes in rat hepatic sulfotransferase (SULT) gene expression. In the present study, male Sprague-Dawley rats were treated for 3 consecutive days with doses of phenobarbital (PB) that induce cytochrome P450 2B1/2 expression. The effects of PB treatment on hepatic aryl SULT (SULT1) and hydroxysteroid SULT (SULT2) mRNA and immunoreactive protein levels and on mRNA expression of individual SULT1 and SULT2 enzyme isoforms were characterized. PB suppressed SULT1A1 mRNA levels, increased the expression of the SULT-Dopa/tyrosine isoform, and did not produce significant changes in SULT1C1 and SULT1E2 mRNA expression. In rats injected with the highest test dose of PB (100 mg/kg), hepatic SULT1A1 mRNA levels were decreased to approximately 42% of control levels and SULT-Dopa/tyrosine mRNA levels were increased to approximately 417% of vehicle-treated control levels. Like the SULT1 subfamily, individual members of the SULT2 gene subfamily were differentially affected by PB treatment. PB (35, 80, and 100 mg/kg) suppressed SULT20/21 mRNA expression to approximately 61, approximately 30, and approximately 41% of vehicle-treated control levels, respectively. In contrast, SULT60 mRNA levels were increased to approximately 162% of control levels and SULT40/41 mRNA levels were increased to approximately 416% of vehicle-treated control levels in rats treated with 100 mg/kg PB. These studies support a complex role for PB-mediated effects on the SULT multigene family in rat liver. Because individual SULT1 and SULT2 enzyme isoforms are known to metabolize a variety of potentially toxic substrates, varied responses to PB among members of the SULT multigene family might have important implications for xenobiotic hepatotoxicity.

Animals↗
PubMed1997

Development of an isotope dilution assay for precise determination of insulin, C-peptide, and proinsulin levels in non-diabetic and type II diabetic individuals with comparison to immunoassay.

We describe the application of a stable isotope dilution assay (IDA) to determine precise insulin, C-peptide, and proinsulin levels in blood by extraction from serum and quantitation by mass spectrometry using analogues of each target protein labeled with stable isotopes. Insulin and C-peptide levels were also determined by immunoassay, which gave consistently higher results than by IDA, the relative difference being larger at low concentrations. Insulin, C-peptide, and proinsulin levels were all shown by IDA to be higher in type II diabetics than in non-diabetics, with mean values rising from 22 (+/- 2) to 92 (+/- 8), 335 (+/- 11) to 821 (+/- 24), and 6 (+/- 1) to 37 (+/- 3) pM, respectively. Interestingly, the ratio between IDA and immunoassay values for insulin levels increased from 1.3 in non-diabetics to 1.7 in type II diabetics. The ratio between proinsulin and insulin levels by IDA increased from 0.24 in non-diabetics to 0.36 in type II diabetics, whereas the ratio between C-peptide and insulin levels by IDA decreased from 17.6 to 10.7. This disproportionate change in protein levels between different types of individuals has implications for the metabolism of insulin in the diabetics studied (type II) and suggests that C-peptide levels are not always a reliable guide as to pancreatic insulin secretion. In addition, levels of the 33-residue C-peptide (partially trimmed form) were shown to be less than 10% that of the fully trimmed 31-residue C-peptide levels, and we tested IDA in a clinical context by two post-pancreatic graft studies. IDA was shown to give direct, positive identification of the target protein with unrivaled accuracy, avoiding many of the problems associated with present methodology for protein determination.

C-Peptide↗
PubMed1997

How informal carers cope with terminal cancer.

This article reports selected findings from a qualitative study of informal carers. The study focused on people caring for relatives with terminal cancer and the findings reported here reflect how they cope with their relative's pain and medication. The author recommends that nurses involve carers in the decision making process to alleviate the stress carers experience and utilise their specialist knowledge of the patient.

Adaptation, Psychological↗
PubMed1997

Differential responses in anterior pituitary luteinizing hormone (LH) content and LH beta- and alpha-subunit mRNA, and plasma concentrations of LH and testosterone, in bulls treated with the LH-releasing hormone agonist deslorelin.

Anterior pituitary gland contents of LH and LH beta- and alpha-subunit mRNAs, and circulating concentrations of LH and testosterone, were determined in bulls treated with the LH-releasing hormone (LHRH) agonist deslorelin. Brahman (Bos indicus) bulls (14-month-old) were allocated to two groups and received the following: Control (n = 5), no treatment; Deslorelin (n = 4), four deslorelin implants (approximately 200 micrograms total deslorelin/day) for 36 d. Plasma concentrations of LH were higher in bulls treated with deslorelin on Day 1, had returned to typical levels by Day 8, and did not differ for control bulls and bulls treated with deslorelin from Day 8 to Day 29. Pituitary content of LH on Day 36 was reduced (P < 0.001) in bulls treated with deslorelin (33 +/- 4 ng/mg) compared with control bulls (553 +/- 142 ng/mg). Relative pituitary content of LH beta-subunit mRNA was also reduced on Day 36 in bulls treated with deslorelin (Control, 0.65 +/- 0.10; Deslorelin, 0.22 +/- 0.04; P = 0.003). However, alpha-subunit mRNA relative content did not differ (Control, 0.73 +/- 0.15; Deslorelin, 1.06 +/- 0.12; P > 0.05). Plasma concentrations of testosterone were increased over the period of the experiment in the bulls treated with deslorelin compared with control bulls. This is the first demonstration of reduced pituitary content of LH beta-subunit mRNA and LH, and unaltered content of alpha-subunit mRNA, in bulls treated with LHRH agonist. This was associated with apparently typical plasma concentrations of LH and elevated plasma testosterone. The anterior pituitary in bulls treated with LHRH agonist, therefore, undergoes classical desensitization and downregulation, but plasma LH and testosterone are not suppressed.

Animals↗
PubMed1997

Work-up of patients with malignancy after an intermediate-probability ventilation-perfusion scan: why don't physicians pursue a definitive diagnosis?

RATIONALE AND OBJECTIVES: The authors determined whether there are specific patient characteristics associated with the clinical decision to eschew further diagnostic testing in patients in whom a ventilation-perfusion (V-P) scan indicates intermediate probability of pulmonary embolism (PE). MATERIALS AND METHODS: The authors reviewed all intermediate-probability V-P scans obtained in a 12-month period. Patients were divided into two groups. Group 1 comprised patients in whom a definitive diagnosis of PE was not obtained and who were not treated for PE (n = 57); group 2 comprised patients in whom the diagnosis of PE was confirmed or excluded and who, if PE was confirmed, received appropriate treatment (n = 14). Age, gender, frequency of malignancy, and survival of patients in groups 1 and 2 were compared. RESULTS: The frequency of malignancy was significantly greater in group 1 than in group 2 (P = .012). Although the estimated 2-year survival of group 1 patients was significantly less than that of group 2 patients (P = .039), this difference is likely due to confounding by age and malignancy. CONCLUSION: When an intermediate-probability V-P scan is obtained, physicians are significantly less likely to pursue a definitive diagnosis of PE in patients with malignancy.

Aged↗
PubMed1997

The secalosides, novel tumor cell growth inhibitory glycosides from a pollen extract.

The pollen of rye (Secale cereale) was shown to contain a biologically highly active family of glycosides called the secalosides. Secalosides A and B (1), both of molecular formula C46H51-NO24, were found to be epimeric esters of (2-oxo-3-indolyl)acetic acid (4). They are made up, in addition to this heterocyclic aglycon I (4), of three hexose building blocks and a carbocyclic aglycon II, which is an indan-derived dicarboxylic acid (5). In aqueous solution, secalosides A and B interchanged by epimerization at the chiral center of 4. A further epimeric pair, secalosides C and D (2), contain one additional glucose building block. Secalosides A and B, the racemic aglycon I (4), and 2-oxo-1,2,3, 4-tetrahydroquinoline-4-carboxylic acid (3), which results from 4 by hydrolytic rearrangement, exhibited significant antitumor activity against S180 sarcoma in vivo. IC50 values obtained were about 5 micrograms/mouse for the secalosides and 1 microgram/mouse for 3 and 4.

Animals↗
PubMed1997

Nature's motility blockers: controlling human sperm motility machinery from the outside. Chemical characterization of a peritoneal fluid lipid that induces sperm immobilization.

A molecule isolated from the peritoneal fluids of women undergoing laparoscopy for in-vitro fertilization techniques has been chemically characterized and identified as 1-palmitic-3-phosphorylcholine (lysophosphatidylcholine, LPC). This lipid is able, at physiological concentrations, to completely inhibit sperm motility in vitro in a dose-dependent way. Synthetic LPC induced rapid and complete arrest of sperm motility when added to sperm suspensions at physiological concentrations without any damage to cell membranes. Taken together, these results suggest that LPC may represent a previously unrecognized in-vivo modulator of human sperm motility.

Ascitic Fluid↗
PubMed1997

Use of Fmoc-N-(2-hydroxy-4-methoxybenzyl)amino acids in peptide synthesis.

The use of N,O-bisFmoc-N-(2-hydroxy-4-methoxybenzyl)amino acid derivatives in the synthesis of peptides with difficult sequences has already been described. With these amino acid derivatives the reversible protecting group 2-hydroxy-4-methoxybenzyl (Hmb) for the backbone amide bonds of peptide chains is introduced, and thus the aggregation due to hydrogen-bond interchain association is inhibited. This paper describes the synthesis and use of Fmoc-N-(2-hydroxy-4-methoxybenzyl)amino acid derivatives as an alternative means of introducing Hmb backbone protection. These new monoFmoc derivatives were obtained in higher yield than the bisFmoc derivatives. Coupling yields to the amino peptide resin were the same as those obtained with bisFmoc derivatives, under the TBTU HOBt/DIEA conditions. We also compared different syntheses of a difficult peptide with the Fmoc approach [triple coupling, capping, use of chaotropic agents, backbone protection using monoFmoc (Hmb)Ala] and with optimized Boc chemistry. Both the backbone protection and optimized Boc chemistry approaches gave the desired product in excellent yield and purity.

Amino Acid Sequence↗
PubMed1997

Outcome assessment in epilepsy: comparative responsiveness of quality of life and psychosocial instruments.

PURPOSE: Few data exist on the ability of instruments to detect within-patient change over time in epilepsy, a property referred to as responsiveness. Our aim was to compare the responsiveness of three instruments [i.e., Epilepsy Surgery Inventory-55 (ESI-55) and Washington Psychosocial Inventory (WPSI), both epilepsy specific, and Symptom Checklist-90-Revised (SCL-90-R), non-epilepsy specific]. METHODS: Instruments were administered at baseline and at 1 year in a prospective cohort of surgically (43) and medically (14) treated patients with temporal lobe epilepsy. Coefficient of Responsiveness and relative efficiency were computed for each scale and for the dimensions of mental health, physical health, and role function. RESULTS: The ESI-55 contained the most responsive scales, whereas SCL-90-R contained the largest number of scales with moderate responsiveness. The largest number of scales with low responsiveness belonged to the WPSI. Sensitivity to between-treatment differences in change was highest for ESI-55 and SCL-90-R. The most efficient scales in detecting differences between treatment groups in the mental, physical, and role-function dimensions were ESI-55 emotional well-being, ESI-55 health perceptions, and SCL-90-R hostility, respectively. CONCLUSIONS: Our results support the responsiveness of ESI-55 scales and suggest that SCL-90-R is a responsive tool for the assessment of psychologic function and distress in epilepsy. Comparatively, WPSI is relatively unresponsive to small or medium-size changes.

Adult↗
PubMed1997

A stable isotope dilution assay for the in vivo determination of insulin levels in humans by mass spectrometry.

Insulin levels in humans were measured by a new assay, the isotope dilution assay (IDA), based on stable isotope dilution mass spectrometry. A known amount of a deuterated analog of insulin was used as an internal standard and added to the serum samples before sample processing. After isolation by immunoaffinity chromatography and solid phase extraction, followed by a purification step on reversed-phase microbore high-performance liquid chromatography (HPLC), the insulin-containing fraction was analyzed by mass spectrometry. The relative intensity of the signals due to insulin and its deuterated analog in the mass spectrum was used to determine the concentration of insulin in the sample. Using serum samples of 0.5-2.0 ml, we were able to measure insulin levels in the range of 3-1700 pmol/l in several clinical samples from type II diabetic patients. The basal level of endogenous insulin was also determined in two normal subjects and found to be approximately 20 pmol/l. Insulin secretion was followed after the ingestion of 75 g glucose in one healthy volunteer. Finally, the determination of the insulin level of one hemolyzed post-mortem blood sample, for which immunoassays gave inconsistent results, was performed to help forensic investigations. Our results showed a good correlation with standard immunoassay data, except in six samples where much lower values were obtained by our stable isotope dilution assay, suggesting an overestimation of insulin levels by immunoassay in some cases. As it is not subject to immunological interferences by insulin-related compounds, this new assay has a major clinical advantage in that it avoids confusions related to hyperinsulinemia.

Adult↗
PubMed1996

Des-(27-31)C-peptide. A novel secretory product of the rat pancreatic beta cell produced by truncation of proinsulin connecting peptide in secretory granules.

Insulin and connecting peptide (C-peptide) are produced in equimolar amounts during proinsulin conversion in the pancreatic beta cell secretory granule. To determine whether insulin and C-peptide are equally stable in beta cell granules (and thus secreted in equimolar amounts), neonatal and adult rat beta cells were pulse-chased, and radiolabeled insulin and C-peptide analyzed by high performance liquid chromatography. A novel truncated C-peptide was identified and shown by mass spectrometry to be des-(27-31)C-peptide (loss of 5 C-terminal amino acids). Des-(27-31)C-peptide is a major beta cell secretory product, accounting for 37.4 +/- 1.6% (neonatal) and 8.5 +/- 0.6% (adult) of total labeled C-peptide in secretory granules after 10 h of chase. Des-(27-31)C-peptide is also secreted in a glucose-sensitive manner from the perfused adult rat pancreas, accounting for approximately 10% of total C-peptide immunoreactivity secreted. Human C-peptide is also a substrate for truncation in granules. Thus, when human proinsulin was expressed (infection with recombinant adenovirus) in transformed (INS) rat beta cells, human des-(27-31)C-peptide was secreted along with the intact human peptide and both intact and truncated rat C-peptide. In addition to truncation, 33.1 +/- 1.2% of C-peptide in neonatal but not adult rat beta cell granules was further degraded. Such degradation was completely inhibited by ammonium chloride (known to neutralize intra-granular pH), whereas truncation was only partially inhibited by approximately 50%. In conclusion, a novel beta cell secretory product, des-(27-31)C-peptide, has been identified and should be considered as a potential bioactive peptide. Both truncation and degradation of C-peptide are responsible for non-equimolar secretion of insulin and C-peptide in rat beta cells.

Aging↗