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Biomedical subjects

R A Decker

Publications and source records attributed to R A Decker.

34 records · Page 2Linked to original sources
PubMed1991

Adrenocortical carcinoma.

Ten patients, seven women and three men, ages 47 to 76 years (mean 58.6 years), treated for adrenal cortical carcinoma between 1971 and 1989, were reviewed. Three (30%) of the tumors were nonfunctioning. The remaining seven (70%) were functioning, six of them occurring in women. Common presenting features were hormonal excess, distant metastases, weight loss, and abdominal pain. The primary tumor was resected in all patients, only two of whom had disease confined to the adrenal gland. Tumor diameter ranged from 9 to 21 cm (mean 15.7 cm). Inferior vena caval or right atrial extension of tumor thrombus was present in two patients. Excluding two deaths from postoperative complications, seven patients died of their disease after a mean survival of 25 months (range 2 to 84 months). Of seven patients who received o,p'-DDD treatment for metastatic or recurrent tumor, three (43%) had an objective response. In two patients, tumor regression was complete and was associated with prolonged survival. The first patient underwent resection of recurrent tumor on two occasions in addition to receiving o,p'-DDD and survived 84 months. The second patient had complete regression of pulmonary and liver metastases confirmed at laparotomy and thoracotomy and remains free of disease at 78 months. None of the five patients treated with various combinations of cytotoxic chemotherapy had an observable response, and no measurable effect was seen in a single patient following abdominal radiotherapy. It is concluded that resection for local recurrence may prolong survival and that significant and lasting tumor regression is possible with o,p'-DDD administration. Beneficial results from cytotoxic agents, however, could not be demonstrated.

Adrenal Cortex Neoplasms↗
PubMed1990

Evaluation of children with multiple endocrine neoplasia type IIb following thyroidectomy.

Medullary thyroid carcinoma (MTC) develops in all patients with multiple endocrine neoplasia type IIb (MEN IIb), a rare syndrome that either occurs sporadically or is inherited in an autosomal dominant pattern. The MTC in patients with MEN IIb has been reported to be biologically aggressive with onset at a young age and rapid progression as evidenced by widespread metastases and death, frequently in the teenage years. Seven children, aged 2 to 11 years (mean, 7 years), from three kindreds with MEN IIb were evaluated for evidence of tumor recurrence 3 to 10 years following thyroidectomy. In one child, age 11, a thyroid mass was palpable preoperatively. However, in the remaining six children (aged 2 to 10 years), the diagnosis of MTC was established by an increased concentration of plasma calcitonin (CT), either basally or following pentagastrin (Pg) stimulation. All patients underwent total thyroidectomy with removal of central lymph nodes from the neck. At the time of surgery, six children were found to have bilateral macroscopic MTC, five without and one with cervical metastases. One child (age 2 years) had C-cell hyperplasia, a premalignant precursor of MTC. Currently, five of the seven children are without evidence of recurrent disease clinically and have normal plasma CT levels (less than 0.3 ng/mL) following calcium (Ca) and Pg stimulation 3, 3, 10, 10, and 10 years after thyroidectomy. Two of the seven children have biochemical evidence of residual MTC.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomarkers, Tumor↗
PubMed1989

Multiple endocrine neoplasia.

The MEN syndromes continue to be the focus of considerable interest and research. Since successful treatment requires early diagnosis, proper screening and follow-up of patients at risk is important. In the individual at risk for developing MEN IIa, annual screening should include measurement of the basal and stimulated plasma CT levels, and determination of plasma levels of calcium, PTH, and CEA. Twenty-four hour urine excretion rates of norepinephrine, epinephrine, metanephrine, dopamine, and VMA should also be obtained. It is our recommendation that this screening be continued through the third decade of life. Patients having thyroidectomy for MTC need to be tested annually for recurrent MTC and the development of adrenal medullary disease. All patients at risk for developing MEN IIb should be evaluated in a similar fashion. Recently, several groups using DNA linkage analysis have mapped the gene for MEN IIa to chromosome 10, although the exact location of the gene is yet to be determined. Preliminary linkage studies have mapped the gene for MEN I to chromosome 11. The identification of the genes for MEN I and MEN II will greatly simplify the diagnosis of the disease and perhaps also the therapy of affected patients.

Adrenal Gland Neoplasms↗
PubMed1982

Intestinal filtration-secretion due to increased intraluminal pressure in rabbits.

The mechanism of changes in small intestinal transport due to acutely increased intraluminal hydrostatic pressure (IHP) was investigated in detail using perfused in vivo rabbit intestinal segments. IHP affected passive transport in vivo by increasing effective mucosal surface area in the small intestine (indicated by 3HOH transport and tissue architectural changes) and increasing small intestinal permeability (indicated by a proportionately greater increase in mannitol than erythritol secretory clearance). IHP did not alter ileal blood flow rate measured by radioactive microspheres, despite grossly evident venous dilatation, or active intestinal transport in the ileum as measured by a) in vitro ion transport in the absence of elevated hydrostatic pressure, b) mucosal adenylate cyclase or Na-K-ATPase activities, and c) glucose-stimulated water and electrolyte absorption. Acutely increased IHP appears to influence the hydrodynamics of the mucosal microcirculation in the rabbit ileum to produce a driving force for passive filtration-secretion, which is associated with and possibly augmented by increased tissue permeability and effective surface area.

Animals↗
PubMed1981

Cellular mechanisms of ion transport associated with osmotic gradients in rat small intestine.

1. The electrical potential difference, short-circuit current, tissue conductance, and fluxes of sodium and chloride were measured in rat small intestine in an in vitro chamber preparation in the presence and absence of 100 mM-mannitol on either the mucosal or serosal surface. 2. Mucosal mannitol generally decreased potential difference, short-circuit current, and tissue conductance while serosal mannitol increased the electrical variables. 3. Mucosal mannitol decreased unidirectional movement of sodium and chloride but did not change the net transport of these ions. The change in short-circuit current was therefore ascribed to changes in fluxes of ions other than sodium and chloride. 4. Serosal mannitol increased the unidirectional fluxes of sodium, but not the new transport of this ion. The transport of chloride increased only in the serosal to mucosal direction yielding a net secretion of chloride equal to the change in short-circuit current. 5. The changes in potential difference and short-circuit current caused by mucosal mannitol were dependent on the presence of sodium. The changes due to serosal mannitol were dependent on both sodium and chloride. 6. Changes in undirectional transport of ions, small non-electrolytes, and water due to an osmotic gradient were attributed to changes in the dimension of the lateral intercellular spaces observed in earlier studies. 7. No evidence suggesting that the electrical changes due to the mannitol gradients could be attributed to diffusive or convective flows of fluid, but instead the changes were ascribed to perturbations in the cellular transport mechanisms.

Animals↗
PubMed1981

Effects of methylprednisolone on electrolyte transport by in vitro rat ileum.

Administration of the glucocorticoid methylprednisolone (MP) (30 mg/kg body wt for 3 days) to rats increased intestinal mucosal guanylate cyclase and Na-K-ATPase activities, short-circuit current (Isc), electrical potential difference (PD), net Na absorption, and net Cl secretion and reversed HCO3 transport from secretion to absorption. In the MP-treated animals, removal of HCO3 from both the mucosal and serosal bathing solutions increased Cl secretion but did not alter the Isc, PD, and net Na flux. Removal of Cl abolished the MP-induced increase in Isc but did not affect the MP-induced changes in net Na and HCO3 fluxes. At 6 h, after a single dose of MP, stimulation of guanylate cyclase activity was already maximal, whereas Na-K-ATPase activity was not detectably altered. The changes in intestinal transport properties present 6 h after MP treatment and associated with the increased guanylate cyclase activity were an increase in Isc and PD and a reversal of net Cl absorption to net secretion. These results suggest that an initial response to MP administration is a persistent increase in intestinal guanylate cyclase activity that mediates an electrogenic Cl secretory process, then is followed by a superimposed effect of increased Na-K-ATPase activity that mediates an increase in net Na absorption.

Animals↗
PubMed1980

Mechanisms of electrolyte transport in rat ileum.

The short-circuit current (Isc), potential difference (PD), tissue conductance (Gt), and Na and Cl fluxes in the short-circuit state across rat ileum were studied in Ussing chambers using a variety of bathing solutions. In Ringer solution, Isc exceeded net Na absorption and net Cl secretion occurred. Addition of 10 mM glucose increased Isc, PD, Gt, and net Na absorption, which accounts for 70% of the increase in Isc. Removal of HCO3 from Ringer solution did not alter any parameters but increased net Cl secretion due to a decrease in mucosal-to-serosal Cl flux. Reduction by 50% of the [Cl] in HCO3-free solution decreased the net Cl secretion to the level in Ringer solution and increased net Na absorption. Removal of Cl decreased Isc to the value of the net Na absorption and decreased the Na influx across the mucosal membrane by 39%. Isc and PD were near zero and net Cl absorption was observed in a Na-free solution. These results are consistent with the transport mechanism that consists of 1) an electrogenic Na absorptive process that accounts for the Isc, 2) a neutral NaCl-coupled secretory process, and 3) a system by which HCO3- secretion exchanges for Cl- absorption.

Animals↗
PubMed1975

Enterolithiasis in a confined Hartman's mountain zebra.

Enterolithiasis was observed on necropsy of a Hartman's mountain zebra (Equus zebra hartmannae). A single enterolith had caused obstruction and rupture of the small colon. The gross lesions are described and the possible etiology discussed.

Animals↗
PubMedDate not supplied

Molecular genetics of APUDomas.

It is tempting to speculate that genetic studies of the human APUDomas, particularly those of a hereditary nature, may ultimately provide valuable clues to the molecular basis of malignant transformation in cells of all types, uncover the mechanisms responsible for tumor progression, and perhaps decipher the signals important in the differentiation of normal neural crest-derived tissue. Generally, several strategies have been used in the genetic analysis of these tumors with success. These include (1) cytogenetic examination of recurring chromosomal abnormalities in hopes of pinpointing critical neighboring growth regulatory sequences important in tumor evolution, (2) identification of dominant acting oncogenes in tumor cells, (3) search for recessive inactivated suppressor genes that may regulate cell growth by analyzing tumors for loss of heterozygosity (LOH), and (4) genetic linkage studies of kindreds affected with familial APUDomas to identify and subsequently characterize the predisposition gene using a positional or functional cloning approach. The results of these strategies as they have been employed in the investigation of cutaneous malignant melanoma (CMM), the dysplastic nevus syndrome (DNS), and the multiple endocrine neoplasia (MEN) syndromes are summarized.

Apudoma↗