PubMed Health⌕ Search

Biomedical subjects

J Steers

Publications and source records attributed to J Steers.

14 recordsLinked to original sources
PubMed1999

Preoperative hepatic artery chemoembolization followed by orthotopic liver transplantation for hepatocellular carcinoma.

In our experience, the primary obstacle precluding the widespread use of orthotopic liver transplantation (OLT) for definitive therapy of hepatocellular carcinoma (HCC), even for early-stage disease, is preventing tumor recurrence. Chemoembolization is an attractive strategy to minimize tumor progression before OLT because of its shown antitumor effect, ability to be repeated, and minimal systemic toxicity. Thus, this pilot study was undertaken to determine the tolerability and treatment outcomes of pretransplantation chemoembolization of HCC followed by OLT. Between 1992 and 1997, 27 patients with HCC who had cirrhosis, no extrahepatic metastasis, less than three tumor nodules of less than 5 cm each, and no evidence of vascular invasion on preoperative imaging studies were enrolled onto the protocol. Chemoembolization was performed using Ivalon particles with mitomycin, doxorubicin, and cisplatin. Twenty-four patients completed the protocol with chemoembolization and a liver transplant. The mean United Network of Organ Sharing waiting time was 167 days. Chemoembolization was well tolerated. On examination of the explanted liver, the majority of patients had a single lesion, mean tumor size was 3.66 cm (range, 1.5 to 6 cm), and the majority of patients had stage II disease. None of the transplant recipients has developed recurrent HCC (mean follow-up, 29.2 months; range, 9 to 55 months). The 1- and 2-year disease-free survival rates are 91% and 84%, respectively. In conclusion, chemoembolization followed by OLT is well tolerated and associated with excellent outcomes in selected patients with HCC.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

Success with intestinal failure: from adaptation to transplantation.

Intestinal failure can result from large resections of small intestine (short bowel syndrome) and from failure of normal intestinal motility. The medical management of short bowel syndrome centers around appropriate diet and use of specific medications including experimental trophic factors. Enteral tubes and prokinetic medications can be successfully used to treat patients with intestinal failure as a result of abnormal intestinal motility. Small bowel transplantation may be a treatment option in certain patients with intestinal failure. This article reviews the management of intestinal failure with a recent update on small bowel transplantation.

Adaptation, Physiological↗
PubMed1997

Craniofacial access to the anterior and middle cranial fossae and skull base.

A profusion of surgical approaches to gain access to the anterior and middle cranial fossa and skull base have been described. An attempt has been made to simplify the position by suggesting a classification of surgical approaches and to describe a standard approach (of at most 4 defined osteotomies, or at least 2) to give a craniofacial approach to the anterior and middle cranial fossae, the infratemporal fossa, the orbit and the superior nasal cavity. The full extent of the osteotomies have been likened to an ancient Corinthian face mask, or to the stylized face-mask worn by the comic book hero, Batman.

Adult↗
PubMed1996

Laparoscopic splenectomy in patients with hematologic diseases.

OBJECTIVE: The authors review their initial experience with laparoscopic splenectomy in patients with hematologic diseases. Efficacy, morbidity, and mortality of the technique are presented, and other patient recovery parameters are discussed. SUMMARY BACKGROUND DATA: Laparoscopic splenectomy is performed infrequently and data regarding its safety and efficacy are scarce. Factors such as a high level of technical difficulty, the potential for sudden, severe hemorrhage, and slow accrual of operative experience due to a relatively limited number of procedures are responsible. The potential patient benefits from the development of a minimally invasive form of splenectomy are significant. METHODS: Clinical follow-up, a prospective longitudinal database, and review of medical records were analyzed for all patients referred for elective splenectomy for hematologic disease from March 1992 to March 1995. RESULTS: Laparoscopic splenectomy was attempted in 43 patients and successfully completed in 35 (81%). Therapeutic platelet response to splenectomy occurred in 82% of patients with immune thrombocytopenic purpura and hematocrit level increased in 60% of patients with autoimmune hemolytic anemia undergoing successful laparoscopic splenectomy. The morbidity rate was 11.6% (5 of 43 patients), and the mortality rate was 4.7% (2 of 43 patients). Return of gastrointestinal function occurred in patients 23.1 hours after laparoscopic splenectomy and 76 hours after conversion to open splenectomy (p < 0.05). Mean length of stay was 2.7 days after laparoscopic splenectomy and 6.8 days after conversion to open splenectomy (p < 0.05). CONCLUSION: Laparoscopic splenectomy may be performed with efficacy, morbidity, and mortality rates comparable to those of open splenectomy for hematologic diseases, and it appears to retain other patient benefits of laparoscopic surgery.

Adolescent↗
PubMed1996

Effects of glucose ingestion versus infusion on pulsatile insulin secretion. The incretin effect is achieved by amplification of insulin secretory burst mass.

In the present studies, we used a recently validated canine model to determine 1) if glucose ingestion stimulates insulin secretion by amplifying the pulsatile component of insulin release, and if so, 2) whether this effect is achieved preferentially through burst mass or frequency modulation, and 3) if the mechanism of incretin effect of insulin secretion is mediated via the pulsatile mode of secretion. We report that 30 g of glucose ingestion stimulates an approximately 550% increase in the overall rate of insulin secretion (1.8 +/- 0.2 to 11.6 +/- 1.5 pmol.kg-1.min-1), which is achieved via an approximately 400% increase in the mass of insulin secreted per burst (202 +/- 38 to 1,003 +/- 147 pmol/pulse, P < 0.001) and a approximately 40% increase in burst frequency (8.7 +/- 0.5 to 12.3 +/- 0.6 pulse/h, P < 0.001). Of the insulin secreted after glucose ingestion, 68% (+/-4) was released in discrete secretory bursts. Further analyses showed that the incretin effect of ingested (GPO) versus infused glucose (GIV) is achieved through regulation of pulsatile insulin secretion. Glucose ingestion led to an approximately 70% greater rate of insulin secretion than intravenous glucose delivery (10.0 +/- 1.6 vs. 5.9 +/- 0.9 pmol.kg-1.min-1, P < 0.005, GPO vs. GIV). This incretin effect was achieved by the specific mechanism of an approximately 70% greater pulse mass (930 +/- 196 vs. 558 +/- 97 pmol/pulse, P < 0.02, GPO vs. GIV) but with a comparable pulse frequency (13.1 +/- 0.9 vs. 12.0 +/- 0.5 pulses/h, P = 0.14, n = 9 dogs, GPO vs. GIV). We conclude that in vivo glucose regulates overall insulin secretion almost exclusively by amplification of the pulsatile mode of insulin secretion, and that the incretin effect is achieved by preferential enhancement of insulin secretory burst mass.

Animals↗
PubMed1995

Pulsatile insulin secretion accounts for 70% of total insulin secretion during fasting.

The purpose of the present study was to determine the contributions of discrete insulin secretory bursts vs. basal insulin release to total insulin secretion in vivo. Quantification of the partitioning of pulsatile and basal insulin secretion is complicated by physiological delivery of these pulses into the portal vein and the absence of validated methods of measuring the rates of pulsatile and basal insulin secretion in vivo. We therefore 1) developed a canine model with chronically implanted portal vein catheters, 2) validated an established deconvolution technique as well as a novel direct catheterization technique (Clustcath) for measurement of pulsatile and nonpulsatile insulin secretion rates in this model, and 3) applied these methods to study insulin secretion in the overnight-fasted dog in vivo to determine the contribution of pulsatile vs. basal insulin secretion to total rates of endogenous insulin secretion. Rates of total, pulsatile, and nonpulsatile endogenous insulin secretion measured by Cluscath closely parallel those measured by deconvolution analysis (54 +/- 15 vs. 51 +/- 11, 38 +/- 12 vs. 36 +/- 11, and 16 +/- 4 vs. 14 +/- 4 pmol/min, respectively). Clustcath and deconvolution indicated that the majority of insulin was secreted as pulses (70 +/- 6 and 66 +/- 7%, respectively). These data infer that any process that selectively decreases the pulsatile component of insulin secretion (e.g., diabetes mellitus) will likely have a major impact on total insulin secretion.

Animals↗
PubMed1995

Impact of sampling technique on appraisal of pulsatile insulin secretion by deconvolution and cluster analysis.

Little is known about the optimal experimental conditions for assessing pulsatile insulin secretion in vivo. To address this, we employed a recently validated canine model (n = 12) to determine the consequences of 1) sampling from the systemic circulation (SC) vs. the portal vein (PV), 2) sampling intensity and duration, and 3) deconvolution vs. cluster analysis on assessing pulsatile insulin secretion. PV vs. SC sampling resulted in a approximately 40% higher pulse frequency by deconvolution (9.0 +/- 0.5 vs. 6.6 +/- 0.9 pulses/h, P < 0.02) and cluster analysis (7.5 +/- 0.3 vs. 5.6 +/- 0.6 pulses/h, P < 0.01) due to a higher signal-to-noise ratio (19 +/- 4.8 PV vs. 12 +/- 1.8 SC). PV sampling also disclosed a higher calculated contribution of the pulsatile vs. nonpulsatile mode of delivery to total insulin secretion (57 +/- 4 vs. 28 +/- 5%, P < 0.001). Analysis of the relevance of sampling intensity revealed that 1-min data yielded a markedly higher estimate of pulse frequency with PV sampling than 2-min data (9.0 +/- 0.5 vs. 5.4 +/- 0.5, P < 0.02, deconvolution; 7.5 +/- 0.3 vs. 4.3 +/- 0.6 pulses/h, P < 0.001, cluster). Optimal sampling duration was shown to be 40 min or more. We conclude that the resolving power of the analytical tool, the anatomic site of blood withdrawal, the frequency of blood sampling, and the duration of the total observation interval all significantly influence estimated insulin secretory pulse frequency and the fraction of insulin secreted in pulses. With the assumption that PV 1-min insulin data constitute the "gold standard," our in vivo inferences of 7.5-9.0 insulin pulses/h closely recapitulate in vitro islet secretory activity.

Animals↗
PubMed1994

Etiology and incidence of unconjugated hyperbilirubinemia after orthotopic liver transplantation.

OBJECTIVES: Gilbert's syndrome, or slow bilirubin glucuronidation phenotype, is a common cause of benign hyperbilirubinemia in the general population. There have been only two previously reported cases of Gilbert's syndrome occurring in patients after liver transplantation. This study was conducted to determine the frequency of Gilbert's syndrome in liver transplant recipients. METHODS: The charts of all patients followed by the Mayo Liver Transplant Clinic for 1 yr or more after transplantation, as of June 1992, were reviewed to identify all patients with a consistent pattern of unconjugated hyperbilirubinemia greater than two times the upper limits of normal and with a normal conjugated bilirubin level. These patients were further evaluated to exclude all other causes of hyperbilirubinemia, including biliary obstruction, rejection, viral infection, cholestatic liver disease, and hemolysis. RESULTS: Five of 229 patients (2.2%) had a consistent pattern of unconjugated hyperbilirubinemia. Only three patients (1.3%) had no other identifiable cause of hyperbilirubinemia. CONCLUSIONS: This study was performed to determine the incidence of unconjugated hyperbilirubinemia and particularly to determine the incidence of Gilbert's disease in liver transplant recipients. The apparently low frequency of Gilbert's after liver transplantation may reflect the masking of the diagnosis by other transplant-associated pathology or donor selection bias because of unexplained hyperbilirubinemia. Post-transplant patients who fit the Gilbert's syndrome profile of unconjugated hyperbilirubinemia should have a postprandial bilirubin drawn as a first step. The awareness of this syndrome may avoid a costly and invasive evaluation in the liver transplant recipient.

Bilirubin↗
PubMed1986

Role of head group structure in the phase behavior of amino phospholipids. 2. Lamellar and nonlamellar phases of unsaturated phosphatidylethanolamine analogues.

Three types of analogues of unsaturated phosphatidylethanolamines (PE) have been prepared: phosphatidyl-omega-amino-1-alkanols, N-alkyl-PE's, and C2-alkyl-PE's, with alkyl substitution of carbon-2 of the ethanolamine head group. The physical properties of dioleoyl, dielaidoyl, and 1-palmitoyl-2-oleoyl phospholipids with these head groups have been examined by calorimetry, 31P NMR, freeze-fracture electron microscopy, and X-ray diffraction. N-Alkylation of PE, or substitution of the ethanolamine moiety by 3-amino-1-propanol or 4-amino-1-butanol, decreases the transition temperature of the hydrated gel phase (Tc) and considerably increases the temperature of the lamellar to hexagonal II transition (TH). The pattern of these effects for various PE analogues suggests that head group size and hydrophobicity as well as hydrogen bonding are important determinants of the phase behavior of these lipids. C2-Alkylated PE analogues exhibit several rather surprising properties, notably the ready formation of a quasi-crystalline "high-melting" solid phase even for di-cis-unsaturated species and substantially lower TH values than are observed for the parent PE species. The behavior of these compounds suggests that "hydration forces" can be more important than considerations of lipid "dynamic shape" in predicting the relative stabilities of lamellar vs. nonlamellar phases for at least some zwitterionic phospholipids.

Calorimetry↗