Biomedical subjects
Publications and source records attributed to P Kumar.
Thermal therapies were the initial forms of endoscopic treatment for GI bleeding more than 20 years ago. Other new technologies have emerged, but thermal treatment with multipolar coagulation or heat probe therapy remains as good as newer techniques. Initial hemostasis rates continue to be 90% or greater. However, rebleeding in about 15% remains a problem. The devices are safe and generally affordable.
Immunization by peptides based on the repeat sequences of Plasmodium falciparum or P. vivax antigen(s) have shown inconsistent results during clinical trials in humans. This could be attributed to the lack of T-cell help or antigenic polymorphism. Thus, attention has been focused towards the more conserved non-repeat regions. The present study was undertaken to map the antigenic determinant in the vicinity of region II (outside the repeat) of CS protein of P. vivax. The immunogenicity of the peptide was studied alone and after linking with polytuftsin (PT), using alum and Freund's adjuvant, in inbred strains of mice with different genetic backgrounds. The humoral response and antigen induced T-cell proliferation assays clearly demonstrated the immunomodulatory activity of PT. Comparable results were observed with antigen(s) administered either in alum or Freund's adjuvant. The induction of IgG2a and IgG2b antibody isotypes by both, peptide as well as the conjugate, may indicate that the T-helper response involved is of Th1 type. Further the immunofluorescence studies have shown that antibodies recognized the air dried sporozoites of P. cynomolgi. The results thus show that the above sequence has overlapping B and T-cell determinants and that alum can be substituted for Freund's adjuvant in generating an effective immune response.
1. The effects of raising extracellular potassium concentration ([K+]o) from 3.0 to 5.3, 9.5 or 16.8 mM on chemoreceptor responses to hypoxia, hypercapnia and asphyxia were examined in a superfused in vitro rat carotid body preparation. 2. Single-exponential functions with offset were fitted to the chemoreceptor discharge responses to ramp decreases in Po2. Increasing [K+]o was without effect upon the rate constants of the fitted exponential functions (P > 0.20). Increasing [K+]o, significantly increased the horizontal asymptote (chemoreceptor discharge in hyperoxia) in a non-linear fashion when all levels of [K+]o were included in the analysis (P < 0.001) but not when a comparison was made only between 3.0 and 5.3 mM Ko+ (P > 0.40). The rightward position of the response curves, as quantified by the Po2 at 50% maximum discharge, was linearly related to [K+]o but only when all levels of [K+]o were included in the analysis (P < 0.03). Chemoreceptor sensitivity to [K+]o increased non-linearly as [K+]o was increased but this effect was not dependent upon the Po2 (P > 0.90). 4. Increasing PCO2 in hyperoxia increased chemoreceptor discharge linearly at all levels of [K+]o. Whilst discharge at any level of PCO2 was elevated by increased levels of [K+]o, raising [K+]o did not increase CO2 sensitivity (P > 0.20). Similarly, increasing PCO2 did not increase chemosensitivity to [K+]o. The lack of effect of [K+]o upon CO2 chemosensitivity was also observed as Po2 was decreased to hypoxic levels (P > 0.10). 5. Our data demonstrate that an elevation of [K+]o can increase chemoreceptor discharge in the in vitro carotid body in a PO2- and PCO2-independent manner, suggesting that the PO2-dependent effects of [K+]o, previously reported in vivo may be due to other indirect effects of [K+]o or hypoxia.
BACKGROUND: The impact of sequential trimodality therapy on the pattern of first site disease failure in pathologic Stage IIIA (N2) nonsmall cell lung carcinoma (NSCLC) was analyzed. METHODS: Seventy-four eligible patients with histologically documented Stage IIIA (N2) NSCLC underwent sequential trimodality therapy on Cancer and Leukemia Group B (CALGB) Protocol 8935. Treatment consisted of 2 cycles of induction cisplatin at 100 mg/m2 intravenously (i.v.) (Days 1 and 29) and vinblastine at 5 mg/m2 i.v. weekly for 5 weeks followed by surgery. Surgery included a thoracotomy with resection of the primary tumor and hilar lymph nodes and a mediastinal lymph node dissection. Patients with resected disease then received an additional a cycles of cisplatin at 100 mg/m2 i.v. and vinblastine at 5 mg/m2 i.v. biweekly for 2 total of 4 doses followed by consolidative thoracic irradiation. Patients with completely resected disease received 54 Gray (Gy) whereas those with incompletely resected disease received 59.4 Gy at 1.8 Gy/fraction (fx) once a day. Patients with unresectable disease underwent thoracic radiation therapy (TRT) treatments only to 59.4 Gy at 1.8 Gy/fx without any additional chemotherapy. Disease recurrence was determined by clinical, radiographic, or histologic criteria. Pattern of disease failure was identified by site of involvement at first recurrence as indicated by the CALGB Respiratory Follow-Up Form. RESULTS: Sixty-three of the 74 patients completed the induction chemotherapy as planned. Forty-six of the 63 patients underwent resection of disease whereas the remaining 17 were unresectable. Thirty-three of the 46 resected patients completed the entire adjuvant postoperative chemoradiation treatment as planned. Ten of 17 patients with unresectable disease completed postsurgical TRT. At a median follow-up interval of 27 months (range, 4-43), the 3-year overall survival and failure-free survival were 23% and 18%, respectively, for all 74 eligible patients. Overall, disease failure has occurred in 52 (70%) of the 74 eligible patients: local only: 13 (25%); distant only: 16 (31%); and both local and distant: 23 (44%), (P = not significant [NS]). Ten patients progressed during induction chemotherapy: local only: six patients; and both local and distant failure: four patients. Twenty-eight of 46 resected patients recurred: local only: 1 (4%); both local and distant failure: 11 (39%); and distant only: 16 (57%); (P < 0.001). Disease progression occurred in 14 of 17 patients with unresectable disease: local only: 6; both local and distant sites: 8. Among the 52 total patients experiencing disease relapse, isolated or combined local failure occurred commonly among patients during induction chemotherapy (n = 10, [28%]), in those with unresectable disease (n = 14, [39%]), or in those with resected disease (n = 12, [33%]), (P = NS). However, isolated or combined distant failure was more likely to occur among patients with resected disease (n = 27, [69%]) than either during induction chemotherapy (n = 4, [10%]) or in those with unresected disease (n = 8, [21%]), (P < 0.05). Among patients who relapsed, brain metastases occurred in 13 of 52 (25%) patients overall and in 12 of 28 (43%) patients with resected disease. CONCLUSIONS: Overall, disease failure was just as likely to occur in local, distant, or combined sites on CALGB Protocol 8935 using sequential trimodality therapy in the treatment of pathologic Stage IIIA (N2) NSCLC: Isolated or combined local failure occurred commonly during sequential tri-modality therapy whereas isolated or combined distant relapse was prevalent among patients with resected disease. In addition, isolated local failure was rare among patients with resected disease. The pattern of disease failure on CALGB Protocol 8935 reflects the biology of locoregional NSCLC as much as the therapeutic impact of trimodality therapy.
The purpose of the present study was to investigate the functional consequences of KATP modulation in the normal and the metabolically inhibited guinea-pig isolated diaphragm using the K+ channel openers cromakalim, pinacidil, RP49356 (N-methyl-2-(3-pyridil)-tetrahydrothiopyran-2-carbothiami de-1-oxide) and ZM260384 (2-(2,2-bis(difluoromethyl)-6-nitro-3,4-dihydro-2H-1,4-benzoxazine -4-yl)pyridine-N-oxide) and the K+ channel inhibitors glibenclamide, phentolamine and ciclazindol. All K+ channel openers accelerated the decline in function induced by intermittent tetanic contractions following metabolic inhibition and delayed the development of contracture. Cromakalim also improved the recovery of twitch tension following 10 min intermittent tetanic stimulation in the hypoxic guinea-pig diaphragm preparation. Of the K+ channel inhibitors tested, only ciclazindol, at the highest concentration tested (10 microM), significantly delayed the decline in tetanic tension following metabolic inhibition in the guinea-pig isolated diaphragm. None of the inhibitors significantly accelerated the development of contracture. All inhibitors however, antagonised the actions of the K+ channel opener, cromakalim. The results indicate that opening of KATP can accelerate the decline in function following metabolic inhibition in the guinea-pig isolated diaphragm. In the absence of K+ channel openers however, KATP does not appear to contribute to this decline under the conditions of the present study.
1. In 3-day-old and 3-week-old spontaneously breathing piglets anaesthetized with Saffan, we have studied ventilatory and cardiovascular responses evoked by 5 min periods of hypoxia (breathing 10 and 6% O2). 2. In 3-day-old piglets both 10 and 6% O2 evoked an increase followed by a secondary fall in ventilation, a gradual tachycardia and a renal vasoconstriction, with an increase in femoral blood flow that was attributable to femoral vasodilatation. Arterial blood pressure rose initially but fell towards control values by the 5th minute of hypoxia. 3. The stable adenosine analogue 2-chloroadenosine (2-CA; 30 mg kg(-1) i.v.) evoked bradycardia and renal vasoconstriction, but had no effect on femoral vasculature. These responses were blocked by the adenosine receptor antagonist 8-phenyltheophylline (8-PT; 8 mg kg(-1) i.v.). 8-PT also abolished the secondary fall in ventilation evoked by 10 and 6% O2 and the renal vasoconstriction evoked by 10% O2, but had no effect on the tachycardia, or on the femoral vascular response. 4. By contrast, in 3-week-old piglets both 10 and 6% O2 evoked a sustained increase in ventilation, tachycardia and a rise in arterial pressure with renal vasoconstriction, but no change in renal blood flow and substantial femoral vasodilatation with an increase in femoral blood flow. 2-CA evoked bradycardia and renal vasoconstriction, as in 3-day-old piglets, but also evoked pronounced femoral vasodilatation. 8-PT blocked these responses and the hypoxia-induced femoral vasodilatation, but had no significant effect on other components of the hypoxia-induced response. 5. We propose that there is postnatal development of the ventilatory and cardiovascular responses evoked by systemic hypoxia and of the role of locally released adenosine in these responses: at 3 days, adenosine released within the central nervous system and within the kidney is a major contributor to the secondary fall in ventilation and renal vasoconstriction respectively, whereas at 3 weeks, adenosine makes little contribution to the ventilatory response, or renal vasoconstriction, but is largely responsible for hypoxia-induced vaso-dilatation in skeletal muscle.
OBJECTIVE: To pilot a targeted chemoradiation protocol for patients with advanced carcinoma of the larynx and pharynx that would circumvent upper aerodigestive tract dysfunction related to major oncologic surgery. DESIGN: Weekly intra-arterial infusions of supradose cisplatin (150 mg/m2 per week x 4) rapidly delivered to the tumor bulk, simultaneous intravenous sodium thiosulfate for systemic drug neutralization, and conventional external-beam irradiation (1.80-2.00 Gy per fraction x 35) were used. Between February 1991 and April 1994, 42 patients were treated who would otherwise have required a major resection of the tongue base, pharyngeal wall, or larynx. MAIN OUTCOME MEASURES: Tumor response, toxic effects, disease control above the clavicle, preservation of the larynx, maintenance of oral nutrition, and overall and disease-related 2-year survival. RESULTS: Three complications were related to the weekly transfemoral superselective intra-arterial procedures performed 160 times. Grade 3 to 4 chemotoxic effects were infrequent, occurring in 9 (5.5%) of 160 cycles, and only 1 patient required a radiotherapy break because of severe mucositis. A complete response in the primary site was obtained in 36 (86%) of 42 patients, 2 of whom had residual disease in the neck. Median follow-up was 13 months (range, 3-46 months). To date, there have been 5 recurrences: 2 regional and 3 distant. The 2-year overall and disease-related survival was 64% and 76%, respectively. The rate of disease control above the clavicle at 2 years was 86%. CONCLUSIONS: We believe this chemoradiation protocol represents an effective management scheme for patients with advanced head and neck cancer while minimizing dysfunction and possibly improving survival.
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An L-shaped scalp flap based on the parietal branch of the superficial temporal artery is described to reconstruct the moustache in a young male patient who suffered from nitric acid burns of the face. This provides a simple technique as an alternative to microvascular technique for moustache reconstruction. The donor area morbidity was minimal.
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We compared the respiratory responses to breath-by-breath alternations of air and 14% oxygen (hypoxia run), air and 5% CO2 (CO2 run) or air from two gas lines (control run) at ambient temperatures of 25-26 degrees C and 30-31 degrees C in nine kittens at 3-7, 11-18 and 30-39 days post-natal age. Chemoreflex responses were measured from alternations in inspiratory and expiratory variables during test runs and compared with those of control runs. At 25-26 degrees C, no significant respiratory alternations were present in hypoxia runs at days 3-7, while alternations were significant at older ages. In CO2 runs alternation was significant at each age group. At 30-31 degrees C, no significant respiratory alternation was present in either hypoxia or CO2 runs for any age group. Thus respiratory chemoreflexes decrease at a warmer environmental temperature in kittens. This may explain how elevated environmental temperature predisposes neonates to respiratory failure.
To investigate differences in the postnatal development of the respiratory peripheral chemoreflex response to hypoxia and to CO2, we measured the responses to switching inspired gas on an alternate breath basis between two air lines (control runs), air and 14% oxygen (hypoxia runs) and air and 5% CO2 (CO2 runs) in nine kittens studied sequentially during quiet sleep between 3-7, 11-18, 24-31 and 35-39 days of postnatal age. The response was quantified in terms of the breath-by-breath alternations in respiratory volumes, durations and flows. There was little response to control runs at any age. The hypoxia response was not different from control at days 3-7 but became significantly different at older ages. In contrast, the CO2 response was different from control in each age group. The pattern of response was different between hypoxia runs and CO2 runs until 35-39 days, when the patterns became similar. The results show that chemoreflex responses to CO2 are present even at an age when hypoxia sensitivity is low.
Eighty-six hypertensive patients with clinical suspicion of renovascular hypertension (RVH) were evaluated by captopril renal scintigraphy (CRS) and intra-arterial digital subtraction angiography (IADSA) to determine the usefulness of CRS in the diagnosis of RVH and to predict the outcome of revascularization procedures. Technetium 99m-diethlenetriaminepentaacetic acid (DTPA) renal scintigraphy was performed on 2 consecutive days before and after captopril administration. Captopril renal scintigraphy was considered positive if there were changes in the time activity curve according to the criteria specified by the American Society of Hypertension working group. Captopril renal scintigraphy data were compared with presence or absence of anatomic renal artery stenosis (RAS). Of 86 hypertensive patients investigated, 45 had RAS. Aortoarteritis was the cause of RAS in 40 (89%) patients. Revascularization was done in 25 patients, and response to revascularization was compared with that of captopril renography. Compared with IADSA, CRS showed a sensitivity of 82.8% and a specificity of 98.2%. Fourteen patients had bilateral RAS on IADSA. In these patients, CRS was suggestive of bilateral disease in seven patients, unilateral in four, and negative in three. Comparison of CRS with the results of revascularization showed a sensitivity and specificity in detecting curable RAS (RVH) of 95% and 100%, respectively (positive predictive value, 100%; negative predictive value, 85%). In conclusion, we found CRS to be useful in the diagnosis of RVH due to aortoarteritis.
Plasma concentrations of endothelin-1 (ET-1) have been reported to be elevated in children and adults with pulmonary hypertension. We hypothesized that infants with persistent pulmonary hypertension of the newborn (PPHN) have elevated plasma concentrations of ET-1. Plasma concentrations of immunoreactive-endothelin-1 (ir-ET-1) were measured using a radioimmunoassay in 20 infants with PPHN and 20 normal term infants. Mean birthweight and gestational age of the infants were comparable in the two groups. The mean plasma ir-ET-1 concentrations were significantly elevated in neonates with PPHN compared to those of normal term infants (2.04 +/- 0.30 versus 1.04 +/- 0.29 pg/mL, p = 0.02). A linear regression analysis demonstrated a significant relationship between ir-ET-1 concentrations and alveolar-arterial oxygen gradient (r = 0.49, p = 0.02) and mean airway pressure (r = 0.49, p = 0.02). There was also a significant correlation between ir-ET-1 concentrations and duration of extracorporeal membrane oxygenation among infants with PPHN (r = 0.44, p = 0.05). We conclude that plasma ir-ET-1 concentrations are elevated in infants with PPHN. The presence of elevated ir-ET-1 concentrations and their positive correlation with disease severity suggests that ET-1 may serve as a marker of the disease severity in these infants. However, further studies are needed to elucidate the role of ET-1 in the pathophysiology of PPHN.
Cleistanthin B, one of the toxic constituents of Cleistanthus collinus, was found to be cytotoxic to normal and tumour cells. In comparison with normal cells, tumour cells were sensitive to lower doses of toxin. The 50% growth inhibition (GI50) values for normal cell lines were from 2 x 10(-5) to 4.7 x 10(-4) M and for tumour cells the values ranged from 1.6 x 10(-6) to 4 x 10(-5) M. Short exposure (30 min) of Chinese hamster ovary (CHO) cells to cleistanthin B at 1-6 micrograms/ml resulted in extensive chromatid and isochromatid breaks and gaps. However there was no significant increase in cell death and DNA strand breaks in cells treated under the above conditions. Cleistanthin B induced micronucleus formation in cultured lymphocytes in a dose-dependent manner. CHO cells treated with high doses of cleistanthin B showed a decrease in cell viability and a concomitant increase in DNA strand-breaks. The cell death appears to be due to apoptosis since nucleosome-like ladders were observed in the treated cells when the DNA was electrophorized in agarose gels.