PubMed HealthSearch

Biomedical subjects

L Herrera

Publications and source records attributed to L Herrera.

At least 19 recordsLinked to original sources

Xenopus laevis oocyte G alpha subunits mRNAs. Detection and quantitation during oogenesis and early embryogenesis by competitive reverse PCR.

The expression of mRNAs coding for different Xenopus laevis oocyte G alpha subunits was analyzed by the PCR technique. Using the nucleotide sequences of five previously cloned cDNAs for oocyte G alpha subunits [FEBS Lett. 244, 188-192, 1989; FEBS Lett. 268, 27-31, 1990] and the highly sensitive reverse PCR reaction we found that G alpha o, G alpha i-1, G alpha i-3 and G alpha s species are present in oocyte stage VI, G alpha o mRNA being the most abundant transcript. G alpha o mRNA was further quantitated through oogenesis, unfertilized eggs and early embryogenesis stages by a competitive PCR reaction using an 'in vitro' deleted G alpha o mRNA as the internal standard. Using this approach we found that Xenopus G alpha o mRNA levels were constant during oogenesis and unfertilized eggs at a concentration of 3.5 pg of mRNA/stage (5 x 10(5) molecules) and diminish gradually during early embryogenesis, reaching a level of 0.3 pg in the gastrula stage. These findings show that oocyte G alpha o, and perhaps the rest of the alpha subunits, are expressed as maternal mRNAs and could play an important role in signal transduction at the beginning of oocyte cell differentiation.

Animals

The utility of squamous cell carcinoma antigen for the follow-up of patients with squamous cell carcinoma of the anal canal.

BACKGROUND: Thirty-three patients with histologic documentation of squamous cell carcinoma (SCC) of the anal canal underwent prospective serial collection of 234 serum samples for radioimmunoassay of SCC tumor-associated antigen. METHODS: There were 23 female and 10 male patients, with a median age of 55 years. Twenty-two of the 33 patients had multimodality therapy with radiation therapy and chemotherapy as initial treatment. RESULTS: The median follow-up was 22 months (range, 4-52 months), with a median of 13 serum specimens per patient (range, 1-23 specimens). Twenty-eight patients currently have no evidence of disease, 4 patients are alive with disease, and 1 patient died with disease. CONCLUSION: In these 33 patients, the sensitivity of the SCC tumor-associated antigen was 76%, specificity 86%, and positive predictive value 62%.

Adult

Expression and different polarity of aminopeptidase N in normal human colonic mucosa and colonic tumors.

Expression and cellular localization of brush-border enzymes (aminopeptidase N, dipeptidylpeptidase IV, lactase, maltase) in normal human colon, colonic polyps and malignant intestinal tumors were investigated with a panel of monoclonal antibodies reacting with either native or denatured proteins. The enzymes were detected on cryostat sections by indirect immunofluorescence staining, or affinity-purified and analyzed by gel electrophoresis and immunoblotting. Dipeptidylpeptidase IV, lactase and maltase were absent from all samples examined, while aminopeptidase N (APN) was detected at the basal membrane of the epithelial cells in most specimens of colon obtained from individuals free of intestinal tumors. In contrast, APN was frequently localized at the luminal membrane of the surface epithelium in large-intestinal mucosa distal to tumors, adenomas and hyperplastic polyps, and from members of hereditary colon cancer syndrome families. APN was also expressed in colonic tumors, where it was present in an apical cell membrane location in 3/23 adenomas and 14/35 adenocarcinomas examined. No correlation was found between tumor-cell invasiveness (classified by "Dukes" stage) and expression or cellular location of aminopeptidase N. Histologically, all positive tumors were moderately or well differentiated. These results suggest that aminopeptidase N is normally expressed in adult human colon, but epithelial cells in the large and small intestine differ in their ways of sorting this enzyme intracellularly and eventually inserting it into different aspects of their surface membrane, a process which may be altered at an early stage of carcinogenesis.

Aminopeptidases

Incidence of metastases from rectal adenocarcinoma in small lymph nodes detected by a clearing technique.

The incidence of metastases from primary adenocarcinoma of the rectum in lymph nodes smaller than 5 mm is not known. Lymph nodes measuring less than or equal to 5 mm usually are not detected by manual techniques of examination of the surgical specimen. This retrospective analysis describes the results when a lymph node clearing technique that identifies lymph nodes as small as 1 mm was used to treat surgical specimens from 27 consecutive patients with rectal adenocarcinoma who underwent abdominoperineal resection with a curative intent and for whom all pathologic data were retrievable. Nine hundred thirty lymph nodes were found, with an average of 34 lymph nodes per specimen (range 0-88). Seventy-two of the 345 lymph nodes found in patients with Dukes C tumors were found to have metastases. Fifty-six (78 percent) of these 72 lymph node metastases occurred in lymph nodes measuring less than or equal to 5 mm. Three lymph node metastases were found in the perianal zone, 53 in the perirectal zone, and 16 in the pericolonic zone. Lymph node metastases from rectal adenocarcinomas often will occur in lymph nodes smaller than 5 mm. We concluded that the use of lymph node clearing techniques discovers these metastases, thereby offering the potential for enhanced staging of primary rectal adenocarcinomas.

Adenocarcinoma

Prevalence of colorectal polyps in Filipinos. An autopsy study.

From May 1988 to May 1990, a prospective autopsy study was performed in patients who died at the Philippine General Hospital in Manila, Philippines. Patients younger than 10 years of age, patients with a history of large bowel resection, and patients whose deaths were related to trauma were excluded. There were 416 patients; 246 were males, and 170 were females. The mean age was 47 years (range, 11-95 years). Six of the 416 patients (1.4 percent) were found to have polyps. One patient had an inflammatory polyp, one was diagnosed with familial adenomatous polyposis, and one had an associated cecal carcinoma. Five "sporadic" adenomatous polyps were found in the remaining three patients (prevalence rate, 0.7 percent). All of the adenomatous polyps were located distal to the hepatic flexure and exhibited only mild atypia. The mean size was 6.4 mm (range, 2-20 mm). The incidence of colorectal adenomas in Filipinos is low compared with that in age-adjusted Western populations. This finding coincides with a low incidence of colorectal carcinoma. The documentation of a low risk for adenomatous polyps and colorectal cancer indicates that it would be difficult for massive screening programs to demonstrate a significant positive impact on the early detection of colorectal neoplasias in the Filipino general population.

Adolescent

Accuracy of colonoscopy for the detection of colorectal polyps.

The findings at colonoscopy were compared with the pathologic findings of the surgical specimen in 235 patients who underwent a colon resection for a primary colorectal neoplasm from January 1980 to December 1987 at Roswell Park Cancer Institute. Seven patients (3 percent) were found to have synchronous primary colon carcinomas, and 100 patients (43 percent) were found to have synchronous adenomatous polyps identified by colonoscopy and/or pathology. In patients with polyps 10 mm or greater in diameter, the findings on colonoscopy agreed with the pathology report 96 percent of the time. When polyps of all sizes were included, with many less than 5 mm in diameter, colonoscopy agreed with the pathology in 89 percent of patients. When only the area of the colon resected was used to determine the ability of colonoscopy to locate polyps, 58 percent of polyps of all sizes were located. The majority of the missed polyps were adjacent to a carcinoma. One cecal carcinoma was not seen by colonoscopy because of technical inabilities to reach the cecum. A second carcinoma (20 mm x 17 mm) was not seen at the splenic flexure.

Colectomy

Gastroduodenal polyps in familial adenomatous polyposis.

A retrospective review of the medical records of 30 patients with familial adenomatous polyposis who underwent oesophagogastroduodenoscopy was performed to evaluate the spectrum of gastroduodenal polyps. Twenty-five patients (83%) had gastroduodenal polyps. Eighteen patients (60%) had gastric polyps and 21 patients (70%) had duodenal polyps. Five patients (17%) had gastric and 20 patients (67%) had duodenal adenomatous polyps. Three patients (10%) died from an upper gastrointestinal tract adenocarcinoma. Three of nine patients with periampullary adenomas had a normal-appearing papilla of Vater. Since gastroduodenal polyps are common in familial adenomatous polyposis, oesophagogastroduodenoscopy should be performed at the time of diagnosis. Biopsy of polyps as well as biopsy of a normal-appearing papilla of Vater should be performed. Due to their malignant potential, if identified, gastroduodenal adenomatous polyps should be destroyed.

Adenomatous Polyposis Coli

Surgery for recurrent rectal adenocarcinoma in the presence of hydronephrosis.

From January 1974 to December 1989, 16 patients with locally recurrent rectal adenocarcinoma and hydronephrosis underwent exploratory celiotomy with curative intent. There were eight males and eight females. The median age was 61 years. Primary rectal adenocarcinomas were treated with abdominoperineal resection in 12 patients and low anterior resection in 4 patients. Four patients underwent adjuvant radiotherapy, one patient adjuvant chemotherapy, and one patient combination therapy. The median disease-free interval between resection of the primary tumor and recurrence was 18 months. Hydronephrosis was unilateral in seven patients (44%), and bilateral in nine patients (56%). Preoperative evaluation indicated that all 16 patients had local pelvic-perineal recurrence or pelvic recurrence alone. Resection was not possible in any of these 16 patients for the following reasons: 5 patients (31%) had pelvic sidewall involvement and carcinomatosis; 3 patients (19%) pelvic sidewall involvement alone; 2 patients (13%) pelvic sidewall involvement and sacral fixation; and 2 patients (13%) had sacral fixation alone. In the remaining four patients, there was pelvic sidewall involvement by tumor and/or synchronous hepatic metastases, carcinomatosis, or sacral fixation. The median survival after exploratory celiotomy was 8 months in the 16 patients who died of their disease. Unilateral and bilateral hydronephrosis appears to be a contraindication for potentially curative surgical resection in recurrent rectal adenocarcinoma.

Adenocarcinoma

Didelphis marsupialis: a primary reservoir of Trypanosoma cruzi in urban areas of Caracas, Venezuela.

Direct blood examination and xenodiagnosis of 45 sylvatic, peridomestic or domestic mammals from the Caracas valley, Venezuela, revealed trypanosome infection in six of the 24 opossums, Didelphis marsupialis, collected in urban areas. Isolates were successfully made of trypanosomes from four of the opossums, using the parasites which developed in Rhodnius prolixus fed on the infected opossums to infect NMRI mice. The prepatent period, course of parasitaemia, morphology of bloodstream trypomastigotes, tissue tropism of parasites in the opossums and/or mice, host mortality, morphology of parasites in the bugs, and infectivity to mice of parasites in the faeces of infected bugs, were all characteristic of Trypanosoma (Schizotrypanum) cruzi. In mice, the parasites showed marked myotropism; the heart, skeletal muscle and the smooth muscle of the urinary bladder, penis, prostate, seminal vesicle, lung, stomach, jejunum and colon were frequently invaded, and pseudocyts were also occasionally found in the liver, brain and pancreas. The significance of the invasion of the genito-urinary structures as a possible alternative parasite transmission route is discussed. The possible role of D. marsupialis, as a primary reservoir of T. cruzi, in the establishment of foci of Chagas' disease in Caracas and other Latin American cities, is emphasized.

Animals

Morbidity and mortality after pelvic exenteration for colorectal adenocarcinoma.

A retrospective analysis was made of the complications from pelvic exenterations performed over the past 30 years for colorectal adenocarcinoma at the Roswell Park Cancer Institute. Seventy-five patients underwent exenteration, 51 for primary disease (PD) and 24 for recurrent disease (RD). Both total and posterior exenterations were included. Twenty of the fifty-one patients (39%) undergoing exenteration for PD developed severe complications, with an operative mortality rate of 6%. The most common complications were injuries to the ureter or bladder, intra-abdominal abscesses, and anastomotic leaks from the urinary diversion. After exenteration for RD, 12 of 24 patients (50%) developed severe complications, with an operative mortality rate of 4%. The most common major complication was an anastomotic leak from the urinary diversion; this occurred in 33% of all patients with RD (8/24). The authors conclude that, although exenteration for colorectal adenocarcinoma may be performed with a low operative mortality rate, patients must be carefully selected because the associated morbidity rate remains high.

Adenocarcinoma

Local recurrence of rectal adenocarcinoma following preoperative radiation therapy and surgery.

An important therapeutic endpoint of the surgical treatment of rectal adenocarcinoma is to obtain local control. In an attempt to enhance this goal, we started a regimen of treatment consisting of preoperative radiation therapy (PRT), 45 Gy in 5 weeks, followed by surgery 4-6 weeks after termination of the PRT. Depending on the local characteristics of the tumor, either an abdominoperineal resection (APR), a posterior pelvic exenteration (PPE), and a total pelvic exenteration (TPE) were performed. All patients found with distant metastasis were excluded from this study. There were 66 patients: 40 males and 26 females. Fifty six underwent an APR, six a PPE, and four a TPE. Their median age was 56 years. Major complications were intraoperative bleeding (15%); perineal wound infection (21%); abdominal wound infection (9%). Five patients (7.5%) died within 30 days of surgery; two after APR, two after PPE and one after TPE. Median follow-up is 60 months. The overall local recurrence rate is 9.8%. Recurrences related to the Astler-Coller modification of Dukes' stage were 0/21 in A or B1, but 6/40 (15%) when the stages were B2, B3, C1, C2 and C3. In conclusion, we found this treatment approach effective in obtaining local control of the rectal adenocarcinoma and comparable to the results of other series. However, it was associated with significant morbidity and mortality.

Actuarial Analysis

Purification of streptokinase by affinity chromatography on immobilized acylated human plasminogen.

Streptokinase is an extracellular protein produced by several strains of streptococci. It functions in the species-specific conversion of plasminogen to plasmin. In this paper we describe the purification of streptokinase by affinity chromatography on human plasminogen acylated with p'-nitrophenyl p-guanidinobenzoate. The acylated and non-acylated plasminogen and plasmin were coupled to cyanogen bromide-activated Sepharose 4B and evaluated for streptokinase purification. These results show that a homogeneous preparation of streptokinase with high specific activity and high yield can be obtained using acylated plasminogen. This method permits the binding of one milligram of streptokinase per milliliter of swollen gel.

Acylation

Cloning of coliphage-T4 gene pseT and high-level synthesis of polynucleotide kinase in Escherichia coli.

The gene, pseT, of coliphage T4 which encodes polynucleotide kinase (PNK) was cloned directly into an expression plasmid using the polymerase chain reaction. When placed under the control of the trp promoter, the pse T gene can be maintained stably in Escherichia coli and yields high levels of the enzyme upon induction. The system described facilitates purification and provides very high yields of PNK.

Base Sequence

Patterns of recurrence after pelvic exenteration for colorectal adenocarcinoma.

We performed a retrospective review of 68 patients who underwent pelvic exenteration for colorectal adenocarcinoma. Forty-seven patients had surgery for primary disease and 21 for recurrence. Clinical recurrence developed in 30 (44%) of 68 patients overall. Of these, 17 (57%) developed locoregional disease only as their first recurrence. This included nine (56%) of 16 patients with primary disease and eight (57%) of 14 patients with recurrent disease. Clinical recurrence developed in 16 (34%) of 47 patients with primary disease and 14 (66%) of 21 patients with recurrent disease. The overall 5-year survival rates were 43% and 20%, respectively. We conclude that locoregional recurrence remains a significant problem for primary or recurrent colorectal carcinoma even after radical pelvic surgery.

Adenocarcinoma

Perspectives in colorectal cancer.

This paper presents an overview of recent developments pertaining to colorectal adenocarcinoma. It is aimed toward the practicing clinician. Topics discussed include epidemiologic observations; genetic predispositions; molecular biology findings; screening and early detection programs; endoscopy; principles of surgical resection; laser and radioimmunoguided surgery; staging; selection of patients for adjuvant chemotherapy; and considerations regarding biologic response modifiers and pain control in the advanced-disease setting.

Adenocarcinoma