Biomedical subjects
Publications and source records attributed to A Raina.
A persistent left superior vena cava (PLSVC) is a rare abnormality that presents a challenge to the implanter. To our knowledge, this is the first case report of implantation of dual-chamber pacemaker via PLSVC utilizing a steerable stylet (the Locater; St. Jude Medical, Inc., Minnetonka, Minnesota) with chronic follow-up showing stable threshold.
When infected with Leishmania donovani, patients develop specific antibodies that constitute the basis of serodiagnosis. Using immunoblot analysis, we examined the antibody response to antigens of L. donovani in 35 kala-azar (KA) patients and 67 controls. Sera from KA patients recognised numerous antigens with molecular weights ranging from 14-110 kDa. Antigens of 40 kDa, 55 kDa, 65 kDa, 70 kDa and 82 kDa were recognised most frequently. All KA patients produce an antibody response to one or more of these antigens. The majority (83%) of KA cases recognised at least four of these five parasite antigens. The 70 kDa antigen showed the greatest sensitivity for Indian KA, and produced a positive reaction in 94% of patients. This antigen gave 10% false-positive reactions in controls comprising patients with related diseases (i.e. tuberculosis, leprosy and malaria) and in healthy controls. Data indicated that the 70 kDa antigen may include a member of the heat shock protein 70 family. Studies with four clinical isolates of L. donovani showed that the 70 kDa component was expressed in all the strains examined. Immunoblot assay (Western blotting) provided a sensitive diagnostic test for KA patients, and identified the 70 kDa parasite antigen that is promising as a potential target antigen for the development of less complex serodiagnostic assays for KA.
BACKGROUND: Although leucovorin (LV) + 5-fluorouracil (5-FU) is considered the treatment of choice for advanced colorectal cancer in most countries, the optimal schedule of this combination has not yet been established. Low-dose LV appears to be as active as high-dose LV in the daily-times-five regimen, but no randomized study of the levorotatory stereoisomer (6S-LV) given at two different dose levels has been published. PATIENTS AND METHODS: Between November 1991 and June 1994, 422 patients (all with measurable disease previously untreated with chemotherapy) were randomized to 6S-LV (100 mg/sqm/i.v.) + 5-FU (370 mg sqm/15 min i.v. infusion), both administered for 5 days every 28 days (arm A), or to 6S-LV (10 mg/sqm/i.v./5-FU (doses as above), also given for 5 days every 28 days (arm B). The primary endpoint of the study was the comparison of response rates (WHO criteria): the secondary endpoint was the assessment of survival and tolerability. No evaluation of the quality of life or the symptomatic effect of treatment was planned. RESULTS: The response rate was 9.3% in arm A (95% CI: 5.4-13.1), with 2 CR and 18 PR, and 10.7% in arm B (95% CI: 6.5-14.9), with 3 CR + 19 PR, without any significant difference (P = 0.78). The median time to progression was eight months in both groups and overall survival was 11 months, with no difference between treatments. Toxicity mainly consisted of gastrointestinal side effects (mucositis and diarrhoea), which were rarely severe (grade 3-4: 5%-10% of patients) and similar in the two groups. CONCLUSIONS: In this large-scale multicentre trial, the low and high doses of 6S-LV appeared to be equivalent in terms of the biochemical modulation of 5-FU in advanced colorectal cancer although, for several reasons (including the timing and the strict criteria of response evaluation, the high number of patients with unfavourable prognostic factors, the multi-institutional nature of the study, the dose and modality of 5-FU administration), the response rate was lower than that reported in some of the other published studies. Given the considerable difference in economic cost between the two dosages, the use of high-dose 6S-LV in the daily-times-five regimen is not recommended in clinical practice.
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Sequence analysis of a human repetitive DNA sequence (pTRF5.6) revealed considerable homology (76%) to the alphoid consensus sequence. Genomic blots of StuI-digested human DNA, hybridized to pTRF5.6, generated a ladder of bands with each band corresponding to oligodeoxyribonucleotide of an approx. 170-bp repeat, indicating a tandemly arrayed organization of this repeat element within the genome. Genomic hybridization analyses of unrelated individuals belonging to various geographical regions of India, using this alphoid satellite prove, revealed polymorphic bands ranging between 2 and 9 kb. Along with an individual-specific band pattern, several isomorphic bands below 2 kb were also evident. There was very little genetic variability between populations, suggestive of low polymorphism at the inter-population level. Our result suggest that alphoid satellite sequence probe can be used in assessing the genetic diversity of various ethnic groups/populations belonging to different geographical regions.
Various storage treatments on human blood samples have been described with respect to DNA yield, quality and fingerprinting. Blood samples were stored at room temperature, 4 degrees C, -20 degrees C and -70 degrees C for different duration varying from 1, 2, 4 and 8 weeks with or without anticoagulant/preservative (EDTA or Heparin). DNA was isolated from these stored samples, quantitated by spectrophotometry and subjected to DNA fingerprinting using a human alphoid satellite DNA sequence (TRF 5.6) and a 33 mer oligonucleotide (O-chi-1) as probes. The polymorphic DNA bands were apparent between 2 to 9 kb size range and the fingerprints were individual-specific. Our results suggest that higher amount of genomic DNA can be recovered from blood samples stored at temperatures 4 degrees C or below in the presence of EDTA or heparin.
A new neuropeptide hormone was isolated from the corpora cardiaca of the periodical cicadas, Magicicada species. Primary structure of the peptide as determined by a combination of automated Edman degradation after enzymatic deblocking with pyroglutamate aminopeptidase and mass spectrometry is: pGlu-Val-Asn-Phe-Ser-Pro-Ser-Trp-Gly-Asn-NH2. Synthetic peptide assayed in the green stink bug Nezara viridula caused a 112% increase in hemolymph lipids at a dose of 0.625 pmol, and a 67% increase in hemolymph carbohydrates at a dose of 2.5 pmol. Based on these results we designate this peptide, a first from order Homoptera, as Magicicada species-adipokinetic hormone (Mcsp-AKH).
An albumin with a well-balanced amino acid composition and high levels of the essential amino acids was purified to homogeneity from the mature seeds of Amaranthus hypochondriacus. The amino acid composition of this protein is comparable to the World Health Organization recommended values for a highly nutritional protein. The protein is a 35-kDa monomer with four isoforms that can be separated by chromatofocusing. Antibodies raised against one of the isoforms, AmA1, cross-reacted with the other three isoforms. Affinity-purified AmA1 antibodies were used to isolate cDNA clones from a developing-seed expression library. The six immunopositive recombinants obtained were found to be related. The cDNA of the largest clone (1.2 kilobases) has a single major open reading frame corresponding to a 304-amino acid polypeptide. The clone was confirmed by hybrid-selected translation and immunoprecipitation. The size of the immunoprecipitated product was identical to the mature protein. Analysis of RNA and protein in developing seeds showed that AmA1 is synthesized during early embryogenesis, reaching a maximum by midmaturation. No RNA was detected in 1-day-old seedlings although the protein showed delayed breakdown on germination. Expression of the AmA1 gene was found to be seed-specific, as no protein or RNA was detected in other plant tissues.
A [3H]-PBAN (pheromone biosynthesis-activating neuropeptide) analog was synthesized, and binding of the radioligand to a specific PBAN-antiserum was achieved. The inhibition of binding of the radioligand by unlabeled PBAN, several PBAN analogs, and other competitors was studied and a specific radio-immunoassay was developed. Using this radioimmunoassay we found PBAN-like immunoreactivity in methanol extracts of hemolymph and neural tissues from females. Higher levels of PBAN-like immunoreactivity in extracts of brain-suboesophageal ganglion complexes, corpora cardiaca, thoracic ganglia, and abdominal ganglia were observed during the 4-5th h scotophase when compared to the PBAN-like immunoactivity levels during the 6-11th h photophase. On the other hand, the concentrations of PBAN-like immunoreactivity, in the terminal abdominal ganglion were higher during the photophase relative to minimal levels observed during the scotophase, indicating an accumulation before the onset of pheromone production. These differences in concentrations of PBAN were also reflected in the stimulation of in vitro pheromone glands, whereby significant stimulations were obtained by scotophase and photophase brain extracts, scotophase thoracic ganglia extracts, and photophase terminal abdominal ganglia extracts. No detectable levels of PBAN were found in hemolymph extracts during the sampling periods.
The authors report two cases of patients with advanced gastroenteric carcinoma, which developed different cardiotoxicity patterns after the administration of cytotoxic drugs. The first patient showed a picture of dilatative cardiomyopathy with associated symptoms of angina pectoris and congestive heart failure; the second patient presented a cardiac arrhythmia after several administrations of 5-fluorouracil. The possible mechanisms of these toxic effects, as well as the drug interactions are briefly discussed. Cardiotoxicity of cytotoxic drugs should be considered by oncologists even in patients with no previous history of cardiac disease.
A cyclic AMP-independent protein kinase, which strongly inhibits in vitro protein synthesis, was purified to homogeneity from barley embryo by affinity and ion exchange chromatography. The M(r) of the purified enzyme is 95,000 with two nonidentical subunits of M(r) 58,000 and 39,000. The enzyme activity is not stimulated by cAMP, cGMP, or calmodulin. The endogenous phosphate acceptor of this kinase is a protein of M(r) 52,000, was isolated by purified protein kinase immobilized Sepharose column. Using antibodies raised against this protein kinase, the levels of the enzyme during embryogenesis and germination are determined. An inverse relationship has been observed between protein kinase level and rate of protein synthesis.
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Spermidine synthase (EC 2.5.1.16) was purified to apparent homogeneity (about 11 000-fold) from bovine brain by affinity chromatography, with S-adenosyl-(5')-3-thiopropylamine linked to Sepharose as the adsorbent. The enzyme preparation was free from S-adenosylmethionine decarboxylase (EC 4.1.1.50) and spermine synthase (EC 2.5.1.22) activities. The native enzyme had an apparent Mr of 70 000, was composed of two subunits of equal size, and had an isoelectric point at pH 5.22. The apparent Km values for putrescine and decarboxylated adenosylmethionine [S-adenosyl-(5')-3-methylthiopropylamine] were 40 microM and 0.3 microM respectively. Cadaverine and 1,6-diaminohexane could replace putrescine as the aminopropyl acceptor, although the reaction rates were only 6% and 1% respectively of that obtained with putrescine. Ethyl, propyl and carboxymethyl analogues of decarboxy-S-adenosylmethionine could act as propylamine donors. Both the reaction products, spermidine and 5'-methylthioadenosine, were mixed-type inhibitors of the enzyme. On the basis of initial-velocity and product-inhibition studies, a ping-pong reaction mechanism for the spermidine synthase reaction was ruled out.
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