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Biomedical subjects

M F Herrera

Publications and source records attributed to M F Herrera.

At least 37 records · Page 2Linked to original sources
PubMed1995

Comparison of outcomes and complications for open and laparoscopic cholecystectomy in Mexico.

A retrospective analysis of the outcome and surgical complications of two groups of patients undergoing cholecystectomy was performed. Group I consisted of 253 patients who underwent laparoscopic cholecystectomy between 1991 and 1994, and group II was formed by 292 patients who met the same preoperative criteria than patients of group I and underwent open cholecystectomy between 1986 and 1990, prior to the introduction of laparoscopic cholecystectomy in our hospital. General characteristics and associated clinical conditions were similar for both groups. Intraoperative cholangiography was used more frequently in group II whereas preoperative ERCP was performed more frequently in group I patients. There was no operative mortality in any of the groups. There were no statistically significant differences between both groups in terms of type and number of complications.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1995

Clinical behavior and prognostic factors of periampullary adenocarcinoma.

OBJECTIVE: The authors evaluated the outcome and potential prognostic factors of 60 patients with surgically resected periampullary tumors. SUMMARY BACKGROUND DATA: Periampullary carcinomas exhibit different clinical behaviors according to their site of origin. There are no prognostic factors for deciding the type of surgery to be used or for choosing patients with tumors that have a poor prognosis for adjuvant treatment. METHODS: A retrospective review was performed of 15 clinical and pathologic variables encountered among 60 patients with periampullary tumors. Tumors were divided into four groups according to their site of origin. Kaplan-Meier survival curves of the four groups were plotted and differences were evaluated with the log-rank test. Cox's proportional hazards model was used to test for separate and combined independent predictors of disease-free survival. RESULTS: Twenty-nine ampullary carcinomas, 20 ductal pancreatic carcinomas, 7 distal common bile duct carcinomas, and 4 carcinomas of the periampullary duodenum were found. Five-year disease-free survival was 43%, 0%, 0%, and 75%, respectively. According to the Cox analysis, absence of neural invasion and use of adjuvant chemotherapy were significant factors for longer survival of patients with ampullary tumors. Lymphatic invasion was related to a shorter survival in patients with pancreatic carcinoma. CONCLUSIONS: Five-year disease-free survival of patients with periampullary tumors is related to tumor type. Prognosis was better for ampullary tumors if neural invasion was absent and if adjuvant chemotherapy was used. Lymphatic invasion was associated with a shorter recurrence-free survival among patients with pancreatic carcinoma.

Adenocarcinoma↗
PubMed1994

Inguinal herniorrhaphy under local anesthesia: a study of intraoperative tolerance.

Tolerance to inguinal hernia repair under local anesthesia was prospectively evaluated in a consecutive series of 41 patients who underwent hernia repair with local infiltration of 0.75 per cent lidocaine. Intraoperative discomfort was measured by an analog visual scale. All complications were also recorded. Mean intraoperative pain was mild (1.6 +/- 1.4). There were two complications. Wound infection and wound hematoma occurred in one patient each. There was no operative mortality. Normal diet was tolerated the day of surgery in 39 patients, and 30 were discharged from the hospital on the same day. Our series supports good tolerance and a low complication rate when inguinal herniorrhaphy is performed under local anesthesia.

Adipose Tissue↗
PubMed1993

Mediastinal paraganglioma: a surgical experience.

Between October 1960 and January 1991, 5 male and 9 female patients (mean age, 44 +/- 19 years) were seen at the Mayo Clinic because of mediastinal paraganglioma. Nine patients presented with hypertension. In these and an additional patient, the tumors were biochemically active. In 13 patients, the mediastinal mass was localized preoperatively. All patients with functioning tumors received alpha-adrenergic and beta-adrenergic blockade preoperatively. Total resection was performed in 11 patients and partial resection in 2. In 1 patient, the tumor was found at postmortem examination. Five lesions were grossly invasive and nine were noninvasive. Blood pressure returned to normal in 6 of the 8 hypertensive patients whose tumors were totally removed. In 4, catecholamine excretion normalized as well. Tumor multicentricity occurred in 6 patients. In 7 patients, the disease took a malignant course (metastases in 5 and progression of unresectable lesions in 2). The probability of 10-year survival after resection was 50% in the group with malignant tumors, and there were no deaths in the group with benign lesions. Analysis of the DNA cellular content showed no correlation between the ploidy pattern and the behavior of the disease.

Adolescent↗
PubMed1993

Hormone secretion by normal human parathyroid cells in vitro: characterization by the reverse hemolytic plaque assay.

We have recently validated a reverse hemolytic plaque assay (RHPA) for the quantitative measurement of parathyroid hormone release from single isolated parathyroid cells. The information regarding secretory behavior of normal and abnormal parathyroid tissue has been based previously on fluorescent spectroscopy or quantification of immunoreactive parathyroid hormone by radioimmunoassay. Thus, individual differences in secretion and assessment of viability are not clearly measured in these types of experiments. The RHPA has the advantage of allowing measurements of secretory activity in individual viable parathyroid cells. In this report, we have modified the RHPA to measure the release of parathyroid hormone from human cells. This is the first instance of measurement of hormone secretion from human cells, and we present data indicating the specificity of the assay for human parathyroid hormone. The response of normal human parathyroid cells to alterations in extracellular calcium was assessed by two parameters: the ability of an individual cell to secrete parathyroid hormone in response to a stimulus and the recruitment of normal human cells to release parathyroid hormone. This assay will allow elucidation of secretory dynamics in normal and abnormal glands, which may help us to understand the mechanisms involved in parathyroid dysfunction.

Animals↗
PubMed1992

Pheochromocytoma producing multiple vasoactive peptides.

Pheochromocytomas may produce several vasoactive peptides. We studied a 39-year-old man who presented with paroxysmal flushing and abdominal pain with normal blood pressure. Laboratory and radiologic studies established the diagnosis of right adrenal pheochromocytoma, and histologic and ultrastructural examination showed the tumor to be a typical pheochromocytoma. Tissue culture yielded large quantities of norepinephrine and epinephrine. However, immunohistochemical studies, tissue assays, and in vitro cultures documented production of several peptides, including calcitonin gene-related peptide and vasoactive intestinal polypeptide in tumor cells. The patient has been asymptomatic after tumor resection. Production of multiple peptides by this tumor may account for the flushing and lack of hypertension, despite elevated catecholamine levels in this patient.

Adrenal Gland Neoplasms↗
PubMed1992

Evaluation of DNA nuclear pattern as a prognostic determinant in resected pancreatic ductal adenocarcinoma.

From a cohort of 72 patients who underwent radical resection for ductal adenocarcinoma of the pancreas between 1951 and 1980, 62 paraffin-embedded specimens were analyzed by flow cytometry. Patients were divided into two groups according to the length of survival: long-term survivors (19 patients who survived 3 or more years after operation) and short-term survivors (43 patients who died within 12 months after resection). In 30 specimens (48%), the nuclear DNA pattern was diploid, whereas 32 were nondiploid (two tetraploid and 30 aneuploid). There were no significant differences in the number of diploid/nondiploid patterns, the fraction of cells in DNA synthetic (S) phase, or the DNA index between the two groups. These data suggest that there is no difference in the DNA content analysis of patients with pancreatic ductal adenocarcinoma when comparing long-term with short-term survivors following resection.

Carcinoma, Intraductal, Noninfiltrating↗
PubMed1992

The effect of cryopreservation on cell viability and hormone secretion in human parathyroid tissue.

BACKGROUND: To explain the decreased success of cryopreserved versus fresh parathyroid autotransplants, we investigated the effect of cryopreservation on parathyroid function. METHODS: Parathyroid cryopreserved tissue from surgical specimens of 18 patients was analyzed in a comparative fashion with 10 fresh abnormal glands. Cell viability was evaluated by a double-fluorescence technique, and parathyroid hormone secretion was detected from individually dispersed parathyroid cells with the reverse hemolytic plaque assay. The plaque area reflected the amount of parathyroid hormone secreted by each cell, and the percentage of plaque-forming cells represented the number of secreting cells. Feedback regulatory mechanisms remained intact for both fresh and cryopreserved tissue as shown over a wide range of calcium concentrations. RESULTS: The percentage of viable cells from fresh and cryopreserved tissue was always in excess of 88%. No significant difference was noted in the percentage of plaque-forming cells nor the amount of hormone released per individual cell comparing fresh and cryopreserved glands (6 months to 2 years). Specifically, at physiologic calcium concentrations no significant differences existed in the secretory behavior between fresh and cryopreserved tissue. CONCLUSIONS: Without showing decreased viability or parathyroid hormone secretion after cryopreservation, the cause of graft failure in cryopreserved tissue still remains unknown.

Calcium↗
PubMed1991

Incidentally discovered adrenal tumors: an institutional perspective.

With the aim of developing guidelines for investigation and management of adrenal incidentalomas, 2066 patients with adrenal masses were analyzed from a total of 61,054 computerized tomographic (CT) scans done from 1985 through 1989. Excluding patients with previous or concurrent malignancies, adrenal tumors localized after biochemical documentation of disease, and adrenal nodules less than 1 cm, 259 patients (0.4%) remained for analysis. Added to these were 83 patients (total 342) in whom the adrenal tumor had been found elsewhere before referral. There were 136 men and 206 women with a mean age of 62 years. Tumor diameter ranged from 1 to 11 cm (average 2.5 cm). Studies to evaluate biochemical hyperfunction were performed in 172 patients (50%), 2 of whom were found to have cortisol-producing tumors and 5 pheochromocytomas. Histologic proof of diagnosis was obtained in 55 patients at the time of adrenalectomy. Malignancy was discovered in five patients (four primary and one metastatic), the smallest malignant tumor measuring 5 cm. In the 287 patients without histologic diagnoses, a minimum of 1 year of clinical follow-up was obtained in 251 (88%), including repeat CT scan in 156 (54%). None of these patients had clinical or biochemical adrenal abnormalities. We suggest (1) biochemical screening in patients with incidentalomas larger than 1 cm, (2) surgical excision of tumors 4 cm or greater, and (3) a comparison CT scan approximately 3 months after diagnosis in patients with tumors less than 4 cm in whom observation has been chosen.

Adolescent↗
PubMed1991

Cardiac function in massively obese patients and the effect of weight loss.

Massively obese patients are at increased risk for heart disease. Blood volume and capillary flow are increased to supply the excess body mass, and there is a concomitant increase in preload and, often, afterload. The heart compensates for the expanded blood volume by increasing stroke volume and cardiac work to provide increased cardiac output. The result is left ventricular dilatation followed by eccentric left ventricular hypertrophy. Cardiac compensatory reserve is limited, leading, at times, to overt congestive failure. After reduction of the excess body fat, most of the cardiovascular derangements appear to reverse. The authors review the effect of massive obesity on the heart and the cardiovascular consequences of weight reduction.

Heart↗
PubMedDate not supplied

Hürthle cell (oxyphilic) papillary thyroid carcinoma: a variant with more aggressive biologic behavior.

The latest World Health Organization International Classification defines papillary thyroid carcinoma by its "follicular cell differentiation...as well as characteristic nuclear changes". However the oxyphilic (Hürthle cell) papillary carcinoma have nuclei which generally resemble the nuclei seen in oxyphilic follicular carcinomas, and such oxyphilic papillary tumors may behave more aggressively than typical papillary cancers. To further characterize these rare tumors, we identified during a 32-year period 22 patients with oxyphilic papillary cancer and compared them with 1,084 patients with typical papillary cancers and 57 patients with oxyphilic follicular cancers treated by the Mayo surgical group during the same time period. Although typical papillary and oxyphilic papillary cancers were comparable with regards to patient age, tumor size and extent, TNM stage, and prognostic score (AGES), there were significant differences. Compared to typical papillary tumors, oxyphilic papillary cancers had fewer neck nodal metastases at primary diagnosis (5% vs 40%, p less than 0.0001), were more often DNA non-diploid (71% vs 21%, p less than 0.001), and after 10 postoperative years had higher rates of both tumor recurrence (28% vs 11%, p less than 0.0001) and cause-specific mortality (1.7% vs 4%, p less than 0.0005). In these four important respects the oxyphilic papillary cancers more resembled the oxyphilic follicular cancers. For oxyphilic follicular cancers, the frequency of initial neck nodal metastases was 7% (cf 5%); 83% of the oxyphilic follicular tumors were non-diploid (cf 71%), and at 10 years postoperatively the tumor recurrence and cause-specific mortality rates were 28% and 18%, insignificantly different from 28% and 17% seen with the oxyphilic papillary cancers.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

[Prospective evaluation of gastroesophageal reflux in patients with achalasia treated with pneumatic dilatation, thoracic or abdominal myotomy].

INTRODUCTION: Symptomatic gastroesophageal reflux (GER) occurs in 0-20% of patients treated with pneumatic dilation and in 5-30% with cardiomyotomy. However, the prevalence of GER evaluated with esophageal pH-monitoring is unknown. AIM: To investigate the frequency of GER in achalasia patients treated with pneumatic dilation or myotomy. MATERIAL AND METHODS: Patients with achalasia were evaluated prospectively and classified in 4 groups: group A = treated with pneumatic dilation; group B = treated with open abdominal myotomy; group C = transthoracic myotomy; and group D = submitted to laparoscopic abdominal myotomy with antireflux procedure. Esophageal manometry and 24 h pH-monitoring were performed in all patients. GER was defined as a pH < 4 in more than 4% of the total time. RESULTS: Thirty-one patients, 22 women and 9 men, with a mean age of 44.7 years were evaluated. Nine patients had GER symptoms and 22 were asymptomatic. GER was detected with pH-metry in 42% of the total group: 33% for group A, 75% for group B, 44% for group C and none for group D. CONCLUSIONS: Prevalence of GER in achalasia patients treated with pneumatic dilation and surgical myotomy was high. We suggest the inclusion of 24 hr esophageal pH-metry in the follow-up due to the significant prevalence of asymptomatic GER. Minimal hiatus dissection and antireflux procedure were surgical factors related with a lower frequency of GER after achalasia myotomy.

Adult↗
PubMedDate not supplied

[Clinical characteristics and course of severe hypercalcemia caused by primary hyperparathyroidism in surgically treated patients].

AIM: To describe presentation, diagnosis, management and outcome of severe hypercalcemia due to primary hyperparathyroidism in a series of patients. METHODS: Clinical characteristics, presentation, diagnosis, acute preoperative medical management, surgical findings and strategy, short outcome and complications of a cohort of 21 patients with primary hyperparathyroidism (HPT) and severe hypercalcemia (serum calcium > or = 14 mg/dL) were analyzed. This group was selected from a total of 118 patients who underwent surgery for HPT in the time period. RESULTS: Mean age was 47 +/- 17 years-old and the male:female ratio was 4:17. A total of 95% of patients presented one or more symptoms related to hypercalcemia while 62% had an abnormal EKG and 76% also had radiological abnormalities. All patients received intense hydration often associated to diuretics. Uniglandular disease was found in 13 patients, multiglandular involvement was identified in 4 and parathyroid carcinoma was documented in other 4. Normalization of the calcemia was achieved in all patients with benign disease. CONCLUSIONS: Severe hypercalcemia was relatively frequent in our patients with HPT. Most patients were symptomatic and presented radiological or cardiac abnormalities. Surgical normalization of the calcemia was achieved in all patients with benign disease.

Adolescent↗
PubMedDate not supplied

Management of choledocholithiasis found during laparoscopic cholecystectomy: a strategy based on the use of postoperative endoscopic retrograde cholangiography and sphincterotomy.

BACKGROUND: Several strategies have been proposed for the diagnosis and management of common bile duct stones in candidates for laparoscopic cholecystectomy. METHODS: Clinical characteristics, treatment, and outcome of five patients in whom CBDS were demonstrated by intraoperative cholangiography during a laparoscopic cholecystectomy were analyzed. All patients were treated by endoscopic sphincterotomy. Post-treatment outcome was emphasized. RESULTS: Mean age of the patients was 55 years. Four were female and one male. Preoperative liver function tests were within normal range in all patients. Duct stones of a mean size of 0.8 cm were found in the lower third of the biliary tree. Four were retrieved by endoscopic sphincteroplasty using a Dormia basket and in one patient after an unsuccessful endoscopic attempt, an open choledochoduodenostomy was performed. There were no post-treatment complications. At a mean follow-up of 2 years no evidence of recurrent common bile duct obstruction has been found in any patient. CONCLUSIONS: This small series supports the use of postoperative endoscopic retrograde cholangiography and sphincteroplasty in patients with unsuspected common bile duct stones found during laparoscopic cholecystectomy. Retrieval of the stones immediately after surgery at the operative room is recommended.

Adult↗
PubMedDate not supplied

[Antibiotic therapy in secondary peritonitis: towards a definition of its optimal duration].

BACKGROUND: The optimal time period of antibiotic treatment in secondary peritonitis is still unknown. AIM: To prospectively evaluate: 1) The preferred time period of antibiotic treatment in secondary peritonitis by means of a survey applied to a sample of surgeons, and 2) The outcome of a series of patients with secondary peritonitis in whom the length of antibiotic treatment was based on clinical and laboratory indicators. PATIENTS AND METHODS: A survey presenting the case of a patient with acute appendicitis and secondary peritonitis was applied to 100 Mexican surgeons. The optimal length of antibiotic treatment in that particular patient was asked. Results were tabulated and analyzed. Subsequently, 35 patients with secondary peritonitis were prospectively evaluated. Antibiotics were discontinued when fever relapsed and the white blood count normalized. Clinical characteristics, diagnosis, surgical treatment and outcome were analyzed. Recurrence of sepsis was investigated as the main outcome variable. RESULTS: The survey revealed that 96% surgeons recommended antibiotic treatment for a period longer than one week. In our study group median age was 33 years, 21 were male and 14 female. All patients had a surgical abdominal condition associated to secondary peritonitis. Median period of antibiotic treatment was 3 days. In a follow-up of one month there was no persistent or recurrent sepsis in any patient. CONCLUSIONS: This information may impact in determining the total length of antibiotic therapy if our results are reproduced in studies with more patients.

Adolescent↗
PubMedDate not supplied

Persistent hypercalcitoninemia in patients with medullary thyroid cancer: a therapeutic approach based on selective venous sampling for calcitonin.

BACKGROUND: Persistent or recurrent medullary thyroid carcinoma (MTC) can be cured by microdissection of residual metastatic lymph nodes in the neck. Selective venous sampling can be used for localization. The aim of this study is to prospectively analyze our results with a therapeutic approach based on venous sampling, in patients with hyperthyrocalcitoninemia after thyroidectomy for MTC. METHODS: Selective venous sampling for determination of stimulated calcitonin was obtained in all patients after performing a complete laboratory and imaging workup. Patients with a gradient between the suprahepatic vein and the superior vena cava underwent unilateral or bilateral extensive lymph node dissection. We used the gradient between the right and left jugular veins to decide which side of the neck to operate. Calcitonin levels were obtained after surgery and a pentagastrin test was performed one year later if basal levels remained normal. RESULTS: Mean age of the five women with a neck gradient in the selective venous sampling who underwent neck exploration was 45 years. In all patients metastatic lymph nodes were found at the site suggested by the study. Mean positive/resected lymph nodes were 5/20. Postoperative basal and stimulated levels of calcitonin became normal in two patients at one year of follow up. CONCLUSION: Selective venous sampling is useful to localize recurrent MTC.

Adult↗