Search PubMed⌕ Search

Biomedical subjects

L Herrera

Publications and source records attributed to L Herrera.

At least 55 records · Page 3Linked to original sources
PubMed1996

Patterns of recurrence following pelvic exenteration and external radiotherapy for locally advanced primary rectal adenocarcinoma.

BACKGROUND: Local recurrence remains the main site of failure after pelvic exenteration for locally advanced primary rectal adenocarcinoma. This is a report on the patterns of recurrence in a group of such patients treated with pelvic exenteration and radiotherapy. METHODS: Between 1980 and 1992, we treated 49 patients. Thirty-one received preoperative radiotherapy (pre-RT), 4,500 cGy. Six weeks later, we performed posterior pelvic exenteration (PPE) in 21 patients, and total pelvic exenteration (TPE) in 10. Nine patients received postoperative radiotherapy (post-RT), 5,000 cGy after a PPE. Nine patients had surgery only, PPE (n = 7) and TPE (n = 2). RESULTS: Surgical mortality occurred in 16% of those patients who received pre-RT. The median follow-up was 52 months. Recurrences occurred in 23% of those patients who received pre-RT (local, one; local/distant, one; distant, four); in 88% of those patients treated with surgery only (local/distant, four; distant, four); and in 11% of those treated with post-RT (distant, one). The 5-year survival for patients who received radiotherapy was 66 versus 44% for those treated with surgery only. CONCLUSION: Local control of locally advanced primary rectal adenocarcinoma requiring a pelvic exenteration is improved by the addition of radiotherapy. When recurrences do occur they are predominantly at extrapelvic sites.

Adenocarcinoma↗
PubMed1996

Mercury determination by CV-AAS in wastewater and sewage sludge from a stabilization pond system.

The mercury concentrations in wastewater and sewage sludge of a stabilization pond system have been evaluated. The system is built by three parallel facultative ponds followed by two systems of three maturation ponds in series. The samples of wastewater and sludge were digested using nitric acid and placed into a Parr-type bomb for 4 h at 110 degrees C. Mercury was measured by Cold Vapour Atomic Absorption Spectrometry (CV-AAS) at 253.7 nm with sodium tetrahydroborate as reductant. The methodologies were checked with an USEPA quality control sample, a standard reference material from NIST and with another method of mineralization (cold mineralization) showing good results. Concentrations of mercury in wastewater between 1.47 +/- 0.75 microgl(-1) have been found at the entrance of the system and 0.74 +/- 0.0 microgl(-1) at the exit, while in sludge the results were between 0.29 +/- 0.12 microgkg(-1) in the facultative pond and 0.04 +/- 0.02 microgkg(-1) in the second maturation pond (exit).

Journal Article↗
PubMed1996

Normative data stratified by age and education for the Neuropsychological Screening Battery for Hispanics (NeSBHIS): Initial report.

Neuropsychological assessment of monolingual Spanish-speaking people in the United States is both a common practice and an ethical dilemma. Lack of appropriate tests, the absence of norms, use of interpreters, and the multiplicity of in-house translations of commonly used measures add to the problem of accurate assessment. This paper helps address the lack of appropriate measures for the neuropsychological assessment of Latinos in the United States by providing a standardization of the Neuropsychological Screening Battery for Hispanics (NeSBHIS). Normative data on a sample of 300 Hispanic subjects stratified by gender, age, and education are provided. Current results reveal that not one measure of cognitive functioning is free from education effects. Both nonverbal measures and psychomotor speed measures were highly related to education. Age effects were noted on measures of psychomotor speed, visuospatial reasoning, and visuoconstructive skills. Gender effects were found on measures of psychomotor speed and language, with males achieving higher scores than females. The limitations of the current findings are considered. Further research for the validation of the NeSBHIS with clinical populations, as well as further normative data collection at the national and international levels, is needed.

Adolescent↗
PubMed1996

Modified clearing technique to identify lymph node metastases in post-irradiated surgical specimens from rectal adenocarcinoma.

The aim of this study is to describe a modification of the original method of clearing lymph nodes in specimens from rectal adenocarcinoma and its yield in comparison to a control group whose specimens were studied by a manual technique. There were 32 consecutive patients with locally advanced rectal adenocarcinoma. All patients received preoperative radiation therapy (PRT) at doses of 45 Gy, concomitant with 5-fluorouracil at the doses of 450 mg/m2 IV bolus, days 1-5 and 28-33 of PRT; 4-8 weeks later radical surgery with a curative intent was performed. Twenty two specimens were studied by a manual technique consisting of fixation in 10% formalin. Ten specimens were studied with the modified clearing technique consisting of administration through the inferior mesenteric artery of methylene blue; fixation with 10% formalin plus 0.01% of methylene blue; clearing the fat with a sequence of 95% alcohol-100% acetone-100% xylene. In the 32 specimens, 413 lymph nodes were found. Using the manual technique 104 lymph nodes were found (average 4.7 lymph nodes per specimen); 309 lymph nodes by the modified clearing technique (average 30.9 lymph nodes per specimen), (p < 0.0001). Using the manual technique 23 out of 104 lymph nodes (22%) contained metastases. All metastatic lymph nodes measured > 5 mm; 18 out of 23 metastatic lymph nodes were located on the perirectal area (level 2); and five were located in the root of the inferior mesenteric artery (level 5). Using the modified clearing technique 278 out of 309 (89%) lymph nodes measured < 5 mm; 15 out of 309 (4.8%) lymph nodes contained metastases; 9 out of 15 (60%) measured > 5 mm and were located on levels 2 and 5; and six, located on level 5, measured < 5 mm. The modified clearing technique is a quick, easy and reproducible method for identifying lymph nodes in post-irradiated surgical specimens. In comparison to the traditional manual method of searching for lymph nodes, it improves in the detection of small lymph nodes (< 5 mm), allowing better staging in patients with rectal adenocarcinoma.

Adenocarcinoma↗
PubMed1996

Trypanosoma (Schizotrypanum) cruzi: histopathology in mice infected with strains isolated from Didelphis marsupialis from the valley of Caracas (Venezuela).

The histopathological alterations produced in NMRI strain mice by isolates of Trypanosoma cruzi from Didelphis marsupialis captured near human dwellings in the valley of Caracas, Venezuela are described. The donor opossums showed pseudocysts and amastigotes and trypomastigotes only in the heart muscle, and few areas of discrete inflammations and lysis of some muscle cells. Mice were parasitized in the heart, skeletal muscle, jejunum, colon, liver, lung, urinary bladder, penis, seminal vesicle, prostate, pancreas, and brain. All the isolates produced histiolymphocytic inflammation, severe in cardiac and skeletal muscle, and light in the smooth muscle of the intestine and urinary bladder; certain of the isolates produced destruction of muscle fibers. These findings, together with the morphology and behavior reported in previous papers, suggest that the isolates from this mammal reservoir and from the local vector (Panstrongylus geniculatus) belong to the same type. The possible venereal transmission through the parasitosis of the urogenital system is discussed. The necessity for characterization of strains of the parasite that have been isolated from areas of intense urbanization, where the ecological changes have reduced the number of host species, is emphasized; such studies may help to clarify the extreme heterogeneity of T. cruzi and the parasitoses it induces.

Animals↗
PubMed1995

Intraoperative small bowel enteroscopy in familial adenomatous and familial juvenile polyposis.

BACKGROUND: In familial adenomatous polyposis and juvenile polyposis, polyps can occur throughout the gastrointestinal tract. METHODS: We report seven patients with familial adenomatous polyposis and two patients with juvenile polyposis who underwent small bowel enteroscopy at the time of exploratory celiotomy either for colectomy or other pathology. RESULTS: Polyps in the jejunum and/or ileum were noted in five of nine (56%) patients at enteroscopy. In three of nine (33%) patients these polys were adenomatous. Two of these patients had polyps in the jejunum and in the ileum, whereas one patient had jejunal adenomas alone. These polyps were from 3 mm to 30 mm in size. The remaining two patients with polyps had lymphoid hyperplasia in the ileum. All three patients who had adenomas at intraoperative small bowel enteroscopy had duodenal adenomas at esophagogastroduodenoscopy. At the age of 14 years, one patient had an intramucosal carcinoma in a small bowel juvenile polyp. CONCLUSION: Baseline small bowel enteroscopy should be considered at the time of surgical exploration in patients with asymptomatic familial adenomatous polyposis and juvenile polyposis. In patients with duodenal polyps, enteroscopy should be performed at the time of surgery. Biopsy and/or excision of larger polyps should be performed because these polyps may harbor a carcinoma.

Adenomatous Polyposis Coli↗
PubMed1995

Medial thigh myocutaneous flap for covering extended hemipelvectomy.

When a large tumour involves the buttock and anterolateral upper thigh, modifications to the classical hemipelvectomy may be required for its removal. Herein, we report the use of a medial myocutaneous flap for coverage of soft tissue defects produced by such procedures.

Adult↗
PubMed1995

Sphincter-saving surgery with and without pre-operative radiation therapy as treatment for adenocarcinoma of the mid-rectum.

AIMS: To determine if pre-operative radiation therapy induces a local response in patients with complete tumour penetration into the rectal wall and allows for anal sphincter preservation, we compared the results from pathological specimens and local recurrences as measurable end-points in patients treated with pre-operative radiation therapy plus low anterior resection vs. those only treated with low anterior resection. METHODS: From January 1986 to December 1992, we treated 62 patients with mid-rectal adenocarcinoma (5-10 cm from the anal verge as determined by rigid proctosigmoidoscopy with the patient in the jackknife position). Pre-operative evaluation included: complete blood cell count, chemistry profile and the determination of carcinoembryonic antigen, chest X-ray, barium enema or colonoscopy and CT scan of the abdomen and pelvis. Only tumours potentially curative by resection in patients with performance status 0-2 (ECOG) were included. Twenty-one patients received pre-operative radiation therapy at a dose of 45 Gy delivered to the pelvis; 4-8 weeks later a low anterior resection was performed. Forty-one patients were treated with low anterior resection alone. Surgical specimens were classified according to the Astler-Coller modification of Dukes' classification. RESULTS: There were 36 males and 26 females, with a mean age of 56 years. The surgical specimens of those treated only with surgery were classified as: A, 5; B1, 4; B2, 15; C1, 2; and C2, 15. Postirradiated specimens: no residual tumour, 3; A, 4; B1, 4; B2, 7; C2, 3. One surgical death occurred in the group who underwent surgery alone. The median follow-up was 50 months in patients treated with surgery alone vs. 62 months in the combined approach group. Local recurrences occurred in 15/40 patients treated with surgery alone and in 2/21 of those treated with the combined approach (P = 0.043). Anal sphincter continence was classified as excellent by 24/40 patients treated with surgery only and by 18/21 patients treated with the combined approach. The 5-year survival period was 58% in the surgery only group and 82% in the group with combined treatment (P = 0.08). CONCLUSIONS: The use of pre-operative radiation therapy plus low anterior resection was associated with a lower rate of local recurrence and with a higher number of surgical specimens with no lymph node metastases. Thus, this combined treatment modality should be further evaluated as a possible treatment of mid-rectal cancers in good surgical candidates selected for sphincter-saving procedures.

Adenocarcinoma↗
PubMed1995

Nicotine gum, 2 and 4 mg, for nicotine dependence. A double-blind placebo-controlled trial within a behavior modification support program.

The effectiveness of nicotine gum in combination with a behavior modification program was studied. The nicotine dependence of participating smokers (N = 322) was assessed. One hundred sixty-eight smokers were labeled as high nicotine dependent and 154 as moderate to low dependent. In a randomized double-blind procedure, the high-dependent smokers were given gum containing 4 mg of nicotine (87) or 2 mg of nicotine (81) and the smokers with medium or low dependence were given gum containing 2 mg (76) or a placebo gum (78). The smokers were also randomized to familiarizing themselves with the medication a week before quit day (112) or to regular use, that is starting gum use on the quit day (122). In the high-dependent group, sustained and chemically verified nonsmoking rates at 6 weeks, 1 year, and 2 years were, respectively, 60%, 39%, and 34% in the subjects given the 4-mg dose compared with 41%, 16%, and 16% for those using the 2-mg dose. In the group with medium or low dependence, the success rates at the same time periods were 70%, 49%, and 39% for the subjects given the 2-mg dose and 38%, 22%, and 17% for those given placebo gum. The differences in success rates were significant at least at the p < 0.02% level for all comparisons. Familiarizing with the gum as compared with regular use gave fewer reports of side effects, 15% vs 34%, p < 0.001. A trend toward better success rates at 6 weeks, although not statistically significant, was observed for the familiarization group, 61% vs 52%. The study shows that high nicotine-dependent smokers need higher doses of nicotine replacement, in this case the 4-mg dose rather than the 2-mg dose, whereas 2 mg is superior to placebo among less dependent smokers. These results compare favorably with those reported from the more recent nicotine patch therapy.

Adult↗
PubMed1995

Patterns of recurrence in squamous cell carcinoma of the anal canal.

The objective of the study was to identify the patterns of recurrence in patients with squamous cell carcinoma of the anal canal (SCCAC) vs. the size of the primary tumor and its further possible impact on its treatment outcome. We reviewed 78 patients treated between 1975 to 1991. They were classified according to to the AJC/UICC classification. From 1975 to 1985, 16 patients were treated with radical surgery (RS). From 1985 to 1991, 43 patients were treated with radiotherapy (RT) at doses of 45 Gy/4-5 weeks, to the pelvis and a boost of 15-30 Gy to the perineum. Since 1989, in 19 selected patients, 5-FU and mitomycin-C have been added to the RT schedule (C-RT). There were 55 females and 23 males. The overall recurrence rate was 62%. In T1 tumors, no recurrences occurred. The local recurrence (LR) according to treatment approach and T were: radical surgery: T2, 50%; T3, 71%; T4, 100%. Radiation therapy: T2, 25%; T3, 41%; T4, 66%. Chemoradiation therapy: T2, 12%; T3, 40%; T4, 50%. Regional recurrences were in RS: T2, 16%; T3, 28%; T4, 100%. RT: T2, 0%; T3, 16%; T4, 33%. C-RT: T2, 0%; T3, 20%; T4, 25%. Distant recurrences were in RS: T2 and T3, 0%; T4, 66%. In RT: T2, 0%; T3, 8%; T4, 33%. In C-RT: T2, 0%; T3, 8%; T4, 50%. In T1 patients, no recurrences were observed. In T2 tumors the recurrence pattern was local. In T3 tumors it was locoregional and to the groin area. In T4 tumors it was locoregional and distant.(ABSTRACT TRUNCATED AT 250 WORDS)

Anus Neoplasms↗
PubMed1995

Expression of interferons-alpha and -beta, tumor necrosis factor-alpha and transcription factors, IRF-1 and IRF-2, in leukocytes induced during interferon production.

Analysis of gene expression in peripheral blood lymphocytes is of special interest because it could reflect physiological conditions. We have examined the expression and compared the relative amounts of specific mRNAs for interferons (IFN-alpha and IFN-beta), tumor necrosis factor-alpha (TNF-alpha) and interferon regulatory factors (IRF-1 and IRF-2) from interferon primed and Sendai virus induced peripheral blood leukocytes. Results obtained showed that IRF-1 was highly inducible by IFN treatment, IFN-alpha, TNF-alpha and IRF-2 were weakly induced by IFN treatment, and IFN-beta was not inducible by priming the cells with recombinant human IFN-alpha 2b. The IFN-alpha, IFN-beta, IRF-2 and TNF-alpha transcripts increased upon viral infection. The IRF-1 mRNA was rapidly induced by IFN treatment and decreased after Sendai virus infection. Our results show that, in peripheral blood lymphocytes, IFN-alpha and -beta genes have a different response to IFN induction, thus suggesting different regulatory mechanisms for IFN induction of type I IFN genes in peripheral blood lymphocytes.

DNA-Binding Proteins↗
PubMed1994

Cloning of a Xenopus laevis muscarinic receptor encoded by an intronless gene.

The Xenopus laevis oocyte has endogenous sites that bind muscarinic agonists, which have been pharmacologically characterized as M3 and/or M1 receptor subtypes. In order to define the molecular identify of the receptor protein we have analyzed a Xenopus oocyte cDNA library and cloned a 2.9 kb cDNA fragment encoding a muscarinic receptor (xMR). The deduced amino acid sequence reveals a protein of 484 residues with an apparent molecular weight of 54,188 Da. Amino acid comparison with previously cloned mammalian muscarinic receptors showed a 78% identity with the human m4 subtype, presenting at the same time clustered differences within the amino-terminal region and third intracellular loop Genomic Southern analysis displayed the presence of one main gene belonging to this subtype, and the PCR analysis revealed an intronless gene.

Amino Acid Sequence↗
PubMed1994

Could the piggyback operation in liver transplantation be routinely used?

OBJECTIVE: To determine if orthotopic liver transplantation with inferior vena cava preservation, performed without using caval cross clamping or venovenous bypass, can minimize hemodynamic instability and low renal perfusion pressure. DESIGN: A prospective case series of 44 consecutive adult orthotopic liver transplantations, with a maximum follow-up of 30 months. SETTING: An institutional university referral center. PATIENTS: Between November 1990 and May 1993, 39 consecutive adult liver transplant recipients underwent transplantation with the following primary diagnoses: alcoholic cirrhosis (n = 23), viral cirrhosis (n = 9), primary biliary cirrhosis (n = 2), Wilson's disease (n = 2), primary sclerosing cholangitis (n = 1), fulminant hepatic failure (n = 1), and secondary hepatic malignant neoplasm (n = 1); five had repeated orthotopic liver transplantation. INTERVENTION: Orthotopic liver transplantations were performed using the piggyback technique, but with placement of the vascular clamp on the inferior vena cava laterally instead of across it so that it remained patent throughout the anhepatic stage. Favorable anatomic conditions in the recipients were not considered; venovenous bypass was not used. MAIN OUTCOME MEASURES: Intraoperative hemodynamic profile, blood loss and replacement, surgical time and complications, and patient survival. RESULTS: No significant hemodynamic changes with lateral clamping and no increases in surgical complications, rate of retransplantation, blood product requirements, or survival rate compared with the standard procedure. CONCLUSION: The piggyback operation could be routinely used in orthotopic liver transplantation.

Adult↗
PubMed1994

Efficient expression and secretion of recombinant alpha amylase in Pichia pastoris using two different signal sequences.

We have cloned and expressed a bacterial thermostable alpha amylase gene in Pichia pastoris using the methanol-controlled alcohol oxidase (AOX1) promoter. Two integrative vectors were constructed with two different secretion signal sequences in order to obtain efficient secretion of the protein. One vector contains the structural gene encoding the mature alpha amylase fused to the SUC2 gene signal sequence from Saccharomyces cerevisiae. In the other vector, the alpha amylase is expressed with its own signal sequence. In both cases, the alpha amylase were secreted into the culture medium with high efficiency, around 2.5 and 0.9 g/l respectively.

Alcohol Oxidoreductases↗
PubMed1994

Resonance energy transfer determination of the distance between the four cysteine-364 residues in Saccharomyces cerevisiae phosphoenolpyruvate carboxykinase.

Each of the four subunits of the Saccharomyces cerevisiae phosphoenolpyruvate carboxykinase has one cysteine residue (Cys-364) that is protected against alkylation by MnATP and that is thought to be located at (or close to) the active site (M. Alvear, M. V. Encinas, S. Latshaw, R. G. Kemp, and E. Cardemil, 1992, Biochim. Biophys. Acta 1119, 35-38). To determine the distance relationships between these residues within this tetrameric enzyme, we have derivatized one of these reactive thiols with N-acetyl-N'-(5-sulfo-1-naphthyl) ethylenediamine (AEDANS) and the others progressively with 4-[N-[(acetoxy)ethyl]-N-methylamino]-7-nitrobenz-2-oxa-1,3-diazole (ANBD). In the doubly labeled protein nonradiative singlet-singlet energy transfer between AEDANS (donor) and ANBD (acceptor) was observed. The efficiency of the energy transfer is proportional to the number of occupied acceptor sites. From these data it has been determined that one of the acceptor sites is 33 A from the donor, and the remaining two sites are 44-46 A from the donor. Cross-linking experiments revealed that mainly cross-linked dimers were produced upon reaction of the enzyme with o-phthalaldehyde and dithiobissuccinimidylpropionate. We interpret these results as an indication that this tetrameric enzyme is most likely composed of an association of two dimers.

Amino Acid Sequence↗