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Biomedical subjects

H Vargas

Publications and source records attributed to H Vargas.

At least 55 records · Page 3Linked to original sources
PubMed1994

Balloon dissection facilitated laparoscopic extraperitoneal hernioplasty.

BACKGROUND: With the goals of minimizing perioperative morbidity and obtaining direct inguinal access without transgressing the peritoneal cavity, we developed a balloon dissection device to facilitate laparoscopic extraperitoneal hernioplasty. PATIENTS AND METHODS: We have performed balloon facilitated dissection on 113 patients (105 males) on an outpatient basis. Some patients were repaired under regional anesthesia. A total of 150 hernias have been repaired: 72 indirect, 70 direct, 3 scrotal, 2 sliding, 2 spigelian, and 1 femoral. RESULTS: Mean operating time was 60 minutes. All patients were ambulatory on discharge. Half reported minimal or no immediate postoperative pain. Over 80% had only minimal irritation or discomfort on the third postoperative day. Nearly 60% returned to work within 2 weeks. None required hospital readmission for an immediate complication of hernioplasty. With a mean follow-up of 6.3 months, only three recurrences are reported. Except for one persistent neuropathy which resolved after staple removal, there were no significant complications. CONCLUSIONS: We conclude that balloon dissection facilitates laparoscopic extraperitoneal hernioplasty and obviates the need for general anesthesia. Our approach minimizes perioperative pain. It can be done on an outpatient basis and permits prompt return to full activity including physical work.

Adult↗
PubMed1994

Small bowel cancer: epidemiological and clinical characteristics from a population-based registry.

OBJECTIVES: Data on small bowel cancers are scarce, and are derived primarily from hospital series. Our aim was to examine the epidemiological and clinical characteristics of these rare cancers. The database is population-based registry with complete ascertainment. It is thus free of the selection bias innate to hospital series. METHODS: Review of the Utah Cancer Registry for all small bowel cancers from 1966 through 1990. For comparison, other cancers were reviewed for incidence and relative survival rates. RESULTS: There were 328 small bowel cancers, including 136 (41%) carcinoids, 80 (24%) adenocarcinomas, 72 (22%) lymphomas, 36 (11%) sarcomas, and four (1%) unclassified. The overall age-adjusted incidence per 100,000 was 1.4 for small bowel cancers compared to 35.7 for colorectum and 92.9 for breast. Small bowel cancers occurred most frequently in the sixth and seventh decades of life, and were more common in men. Carcinoids, lymphomas, and sarcomas occurred in order of decreasing frequently in the ileum, jejunum, and duodenum; the reverse was true for adenocarcinomas. Distant metastases occurred in 35 (27%) carcinoids, 14 (28%) adenocarcinomas, 17 (26%) lymphomas, and 10 (33%) sarcomas. Surgery was the primary form of therapy in 108 (79%) carcinoid patients, 80 (49%) adenocarcinoma patients, 52 (72%) lymphoma patients, and 26 (72%) sarcoma patients. The overall 5-year relative survival rate for small bowel cancers was 54%; 83% for carcinoids, 25% for adenocarcinomas, 62% for lymphomas, and 45% for sarcomas. Overall survival, compared to other cancer sites, was surpassed only by cancers of the prostate, breast, and colorectum. CONCLUSIONS: Small bowel cancers consist of several types of rare tumors, each with unique characteristics. The overall prognosis is better than for most common cancers.

Adenocarcinoma↗
PubMed1993

Medial septal lesions disrupt spatial, but not nonspatial, working memory in rats.

In Experiment 1, rats with small medial septal lesions were less able than were control rats to remember the location of the arm of a Y maze they had been forced to enter on the preceding sample run. Moreover, as the retention interval between the sample and choice runs on this spatial delayed nonmatching-to-sample (DNMTS) task was increased to 1 and 2 min, the magnitude of the deficit increased. In contrast, these same lesioned rats were not deficient in Experiment 2 in their ability to remember the object they had encountered in the straight alley on the sample run. In fact, when the retention interval was increased to 1 min on this nonspatial DNMTS task, the rats with medial septal lesions were more accurate than were the controls. This pattern of results did not appear to be due to task difficulty, recovery of function, or sequence of training. Rather, these results indicate that damage to the septohippocampal system disrupts spatial working memory more than it disrupts nonspatial working memory.

Animals↗
PubMed1992

Regulation of MHC class I synthesis and expression by human neutrophils.

Human peripheral blood neutrophils (PMN) treated with granulocyte-macrophage CSF (GM-CSF) increase the amount of class I 42-kDa H chain and 12-kDa L chain, beta 2-microglobulin (beta 2m), that they synthesize by 2.1- and 2.6-fold, respectively. To determine whether the increase in translation was associated with an increase in levels of class I H chain transcript, RNA blot analysis was performed on PMN that had been cultured in the presence of GM-CSF. Under no conditions were there increased levels of class I H chain transcript when class I heterodimer protein synthesis was increased. In addition, there was neither an increase in the synthesis of H chain mRNA, as measured by transcription assay, nor an alteration in the degradation rates of class I H chain transcript in PMN cultured with GM-CSF. In situ hybridization demonstrated that both the percentage of PMN that expressed class I transcript and the relative amounts of transcript per cell in GM-CSF-cultured PMN were the same as those in control PMN. Although there is increased translation of class I heterodimer in PMN treated with GM-CSF, there is no increase in its expression on the plasma membrane. The maintenance of constant levels of class I on the plasma membrane is dependent on continued protein synthesis and is maintained by release of class I heterodimer and free beta 2m into the medium. Heterodimer is released in the context of plasma membrane-derived vesicles, whereas beta 2m is released as a soluble protein. Maintenance of constant levels of class I heterodimer on the plasma membrane is also regulated by constitutive internalization. Up to 30% of class I molecules bearing 125I-Fab-labeled mAb to class I are internalized over 2 h at 37 degrees C. Therefore, inducible synthesis of class I by PMN is likely a consequence of post-transcriptional regulation, whereas the continued synthesis of class I heterodimer is required for maintenance of its expression. Furthermore, there is no increase in class I expression, in spite of increased synthesis, due to the release of class I heterodimer and beta 2m and the internalization of class I heterodimer from the plasma membrane. Thus, PMN are capable of post-transcriptional regulation of protein synthesis and are able to modulate the expression of plasma membrane proteins by regulated expression, release, and internalization.

Antigens, Differentiation, B-Lymphocyte↗
PubMed1991

Angiotensin alteration of drug uptake in an experimental model of hepatic metastases.

To evaluate the use of angiotensin-II (A-II) as a means of improving results with intra-arterial infusions of hepatic tumors, 32 New Zealand white rabbits underwent perfusion of VX-2 hepatic implants. Tritium-labeled fluorodeoxyuridine [( 3H]FUDR) was administered via peripheral ear vein in 9 control rabbits (iv), via the hepatic artery in 12 rabbits (HA), and following a constant infusion of A-II in the remaining 11 rabbits (HA/A-II). Biopsies of tumor and normal hepatic parenchyma were taken and tissue levels of FUDR measured. Hepatic artery infusions, both with and without A-II, resulted in a significantly greater tumor uptake of FUDR than the iv infusions (P less than 0.001). More importantly, the tumor/liver ratio of FUDR uptake was significantly greater in the HA/A-II group (3.40) than that in the HA without A-II (0.98) group (P less than 0.001). This difference is due to the decreased FUDR uptake by normal hepatic parenchyma in rabbits undergoing A-II infusion; tumor drug uptake is similar for both groups. We conclude that the addition of angiotensin II to hepatic artery infusional chemotherapy significantly improves the tumor/liver ratio of drug uptake in this experimental model of hepatic metastases.

Angiotensin II↗
PubMed1991

Ethanol injection of hepatic tumors.

To assess the efficacy of intratumoral injections of absolute ethanol in the treatment of hepatic tumors, 18 New Zealand White rabbits underwent implantation of two 1-mm3 fragments of the VX-2 carcinoma. The animals were reexplored 2 weeks postimplant and the tumors measured. One nodule was treated by intratumoral injections of 2.28 +/- 0.72 mL of absolute ethanol; the second was injected with an equal amount of normal saline. The animals were sacrificed 4 weeks postimplant, and the tumors were measured and microscopically examined. On gross inspection, tumor size, expressed as the product of the largest and smallest diameters, was 4.59 +/- 3.4 cm2 for the ethanol-injected tumors vs 6.73 +/- 2.1 cm2 for the saline-treated nodules (p = .01). Histologic sections through the largest tumor diameter were microscopically examined using a computerized image analyzer. The mean cross-sectional area of viable tumor was 0.51 +/- 0.3 cm2 for the ethanol-treated nodules vs 2.01 +/- 0.5 cm2 for the saline-treated nodules (p less than .001). Contrast-enhanced CT and MRI studies were able to provide valuable information in terms of tissue characterization, which will be useful in differentiating viable tumor from necrotic tumor and infarcted liver. We conclude that intratumoral ethanol injection inhibits growth of liver tumors in this experimental model and deserves further study.

Animals↗
PubMed1991

Catecholamine concentrations in the hepatic portal system: effect of surgical stress upon portal levels.

The biological effects of a hormone are dependent on the concentration delivered to the target tissue. This is generally best reflected in the arterial concentration. However, the liver is unique in that it receives substantial additional blood flow from the portal venous system. This may be important in the case of the catecholamines, where extraction or spillover from the splanchnic circulation may occur. In this study we examined portal venous catecholamine concentrations in anesthetized, laparotomized rabbits. We compared the values with simultaneously sampled arterial levels to evaluate the effects of the splanchnic tissues upon a wide range of catecholamine concentrations delivered to the liver during a state of stress. Spillover of norepinephrine and extraction of epinephrine were observed in all rabbits. Mean (+/- SEM) arterial norepinephrine concentrations were elevated, 716 +/- 167 pg/ml (n = 11); mean portal concentrations were 178 +/- 37% higher (p less than 0.01), at 1,425 +/- 301 pg/ml, representing net spillover from splanchnic tissues. In addition, significant extraction of epinephrine was observed; arterial concentrations were 2,144 +/- 580 pg/ml (n = 11). Portal levels were 1,205 +/- 382 pg/ml, 38 +/- 7.45% lower than corresponding arterial concentrations (p less than 0.02). Furthermore, there was a concentration-dependent effect upon norepinephrine spillover; the highest arterial norepinephrine concentrations were associated with the lowest splanchnic spillover. This resulted in a negative correlation between the arterial norepinephrine levels and the percent increase from spillover into the portal vein (r = -0.81, p less than 0.003). We conclude that portal venous catecholamine concentrations are significantly different from arterial levels in anesthetized, laparotomized rabbits over a wide range of concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Value of measuring hormone receptor levels of regional metastatic carcinoma of the breast.

To assess the value of measuring the estrogen- and progesterone-receptor content of metastatic nodal disease, 38 women with node-positive breast cancer were prospectively evaluated. Receptor content of the primary tumor and a pathologically confirmed positive node were measured simultaneously using a dual-isotope, dextran-coated, charcoal-binding assay. A receptor content of greater than or equal to 10 fmol/mg of cytosol protein was considered positive for both the estrogen-receptor and progesterone-receptor assays. Overall concordance between the primary tumors and the nodal metastases was 82% (31/38 patients) for the estrogen-receptor measurements and 84% (31/37 patients) for the progesterone-receptor measurements. Paired receptor levels were significantly correlated: r = .745 for the estrogen-receptor measurements and r = .805 for the progesterone-receptor measurements. Despite this correlation, 6 (25%) of 24 patients with an estrogen receptor-positive primary tumor had an estrogen receptor-negative nodal metastasis. Four (20%) of 20 patients with a progesterone receptor-positive primary tumor had a progesterone receptor-negative nodal metastasis. Six (24%) of 25 patients with tumors labeled as hormonally sensitive on the basis of the receptor content of the primary tumor had receptor-negative nodal disease. In reflecting the hormonal status of the more aggressive elements of the primary tumor, receptor levels of metastatic nodes may provide more useful information than the levels of the primary tumor as a guideline for further therapy.

Breast Neoplasms↗
PubMed1988

A comparison of the central and peripheral antimuscarinic effects of atropine and methylatropine injected systemically and into the cerebral ventricles.

We compared the relative abilities of atropine sulfate and methylatropine, injected i.v. and into the cerebral ventricles (icv), to block pharmacological responses mediated through central and peripheral muscarinic receptors. The hypotensive response to i.v. injection of acetylcholine (peripheral muscarinic receptors) was inhibited 50% by i.v. injection of 14.3 nmol (5.5 micrograms)/kg methylatropine and 147.8n molar equivalents (50 micrograms)/kg atropine sulfate. A similar degree of inhibition followed icv injection of 49.4 nmol/kg methylatropine and 384.2 nmol equivalents/kg atropine sulfate, indicating significant leakage out of the ventricular space. The pressor response to icv injection of neostigmine (central muscarinic receptors) also was inhibited more effectively by icv methylatropine than by atropine sulfate. Methylatropine was not effective in blocking central muscarinic receptors when injected i.v.

Acetylcholine↗
PubMed1988

Blockade of brain M2 muscarinic receptors lowers blood pressure in spontaneously hypertensive rats.

Injections of the M2 muscarinic receptor antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP; 1.5-40 micrograms) into the cerebral ventricles of urethane-anesthetized rats caused a dose-related inhibition of the pressor response to intravenously injected physostigmine. A similar reduction was obtained with 1/80th the dose of methylatropine, but not with the selective M1 antagonist pirenzepine. Intraventricular injection of 4-DAMP (6.25-25 micrograms) caused a dose-related reduction in blood pressure in unanesthetized spontaneously hypertensive rats (SHR), but not in normotensive controls. Systolic pressure fell 42 +/- 6 mm Hg at the 25-micrograms dose. Pirenzepine did not lower blood pressure in SHR and inhibited the antihypertensive effect of 4-DAMP.

Animals↗