Indications for the use of parenteral H2-receptor antagonists

Development of acute mucosal ulceration is a complex series of catabolic interactions. Hospitalized patients with duodenal or gastric ulcer, pathologic gastric hypersecretory states (such as Zollinger-Ellison syndrome), gastric outlet obstruction, esophagitis, severe gastritis or duodenitis, sepsis, trauma (particularly head injury or burns), and some patients receiving high-dose corticosteroids are at risk of developing acute stress ulcers. Treatment should be initiated as soon as the patient is identified as being at risk, because measures designed to prevent bleeding or perforation are more effective than those designed to stop bleeding once it supervenes and the cascade of multiple organ failure commences. The presence of acid will trigger the onset of this condition; however, ulceration will not occur if the intraluminal pH can be maintained above 5 by periodic antacid treatment or by H2-receptor blockade. The dosing regimen of antacid or of H2-receptor antagonist should not be fixed, but should be sufficient to keep the gastric pH higher than 5. Antagonists administered via a nasogastric tube are the first line of defense, but 30 to 50 percent of the most ill patients will also be treated parenterally with H2-receptor antagonists. Parenteral H2-receptor blockade therapy is indicated in these patients when the risk of acute or continued ulceration of esophageal, gastric, or duodenal mucosa is high and the oral administration of medication is either not possible or the response to such therapy is unreliable. Parenteral H2-receptor antagonists are rarely administered alone.

Pituitary adenylate cyclase activating polypeptide stimulates release of peptide YY

The purpose of these experiments was to examine the effects of the recently discovered gastrointestinal peptide, pituitary adenylate cyclase activating polypeptide (PACAP), and two structurally related peptides, vasoactive intestinal polypeptide and secretin, on release of peptide YY (PYY) in conscious dogs. Intravenous administration of PACAP-27 or -38 stimulated a dose-related release of PYY; PACAP-27 was more potent than PACAP-38. PACAP-stimulated release of PYY was inhibited significantly by atropine, whereas ganglionic or beta-adrenergic blockade with hexamethonium and propranolol treatment, respectively, did not affect PACAP-induced release of PYY significantly (P > 0.05). These results indicate that PACAP-induced release of PYY is cholinergic dependent and that beta-adrenergic tone and ganglionic transmission do not participate in PACAP-induced release of PYY. PACAP may play a role in the neural regulation of PYY release.

Experimental gene therapy of human colon cancer

BACKGROUND

Gastrin regulates growth of human colon cancer cells by activation of the cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA). Gastrin and 8-Br-cAMP, a membrane-permeable cAMP analog, inhibit growth of HCT116 cells; both stimulate growth of LoVo cells. This dual effect on growth may be explained by relative amounts of the regulatory subunit (RI alpha or RII beta) of PKA within the cancer cells. Antisense oligodeoxynucleotides (ASO) to either RI alpha or RII beta inhibit protein translation of the target mRNA by sequence-specific binding; subsequently, cellular PKA content and the cAMP-mediated growth may be altered. We determined whether ASO to either the RI alpha or RII beta subunit altered the cAMP-mediated growth of HCT116 and LoVo human colon cancer cells.

METHODS

HCT116 cells were treated with RII beta ASO (15 mumol/L, 4 days) and then treated with 8-Br-cAMP (25 mumol/L); tritiated thymidine incorporation was measured after 24 hours, and the cell number was determined on alternate days. Protein and mRNA levels of the RII beta subunit were determined by Western and Northern blotting, respectively. Similar studies with an ASO against the RI alpha subunit were performed on LoVo cells.

RESULTS

RII beta ASO reversed the cAMP-mediated inhibition of growth of HCT116 cells, and RII beta ASO decreased the protein level of the RII beta subunit. RII beta ASO did not alter the basal growth of HCT116 cells. RI alpha ASO reversed the cAMP-mediated stimulation of growth of LoVo cells.

CONCLUSIONS

The regulatory subunits of PKA are potential targets to alter growth of human colon cancer cells. Gene therapy directed to alter specific steps in signal transduction pathways may provide new therapeutic strategies.

Effects of gastrin on 3',5'-cyclic adenosine monophosphate, intracellular calcium, and phosphatidylinositol hydrolysis in human colon cancer cells

Gastrin is a trophic factor for some human colon cancer cells. However, the signal-transduction pathways by which gastrin regulates growth are still unknown. We examined the effect of synthetic human gastrin-17 (G-17) on signal-transduction pathways and cell growth using 4 different human colon cancer cell lines (LoVo, COLO 320, HT-29, and HCT116). G-17 stimulated the production of cyclic AMP in LoVo, COLO 320, and HCT116 cells, while G-17 stimulated phosphatidylinositol hydrolysis and mobilization of intracellular calcium in HT-29 cells. The growth-regulatory effect of G-17 on these colon cancer cells (stimulatory on LoVo, COLO 320, and HT-29 cells; inhibitory on HCT116 cells) was well correlated with the effect of G-17 on the signal-transduction pathway in each cell line. We further examined the effect of a selective cholecystokinin-B type receptor antagonist, JMV 320, on G-17-induced signal-transduction pathways and G-17-regulated growth. In each cell line, the effect of JMV 320 on G-17-induced signal-transduction pathways was well correlated with that on G-17-regulated growth. G-17 appears to regulate, at least to some extent, growth of human colon cancer cells through gastrin receptor-linked signal-transduction pathways that are cell-specific.

Abaloparatide and the Spine: A Narrative Review

Osteoporosis is a common and debilitating condition characterized by diminished bone mass and architecture leading to bone fragility. Antiresorptive medicines like bisphosphonates (and less commonly denosumab) are the typical first-line agents for the medical treatment of osteoporosis. However, newer anabolic agents have been shown to improve bone mass and architecture, as well as reduce fracture risk, to a greater degree than traditional antiresorptive therapies. Teriparatide (human recombinant parathyroid hormone (PTH) 1–34, Forteo, Ely Lilly, Indianapolis, IN), which was the first in class to be approved in the United States, is the most widely used anabolic osteoporosis medicine and has shown significant benefit over traditional antiresorptive therapies. However, abaloparatide (synthetic parathyroid-related peptide (PTHrP), Tymlos, Radius Health, Waltham, MA), the second drug in this family, has recently become available for use. In this narrative review, we review the mechanism, effects, and benefits of abaloparatide compared to alternative treatments as well as discuss the current literature in regard to its effect on osteoporosis-related complications in the spine.

Effects of cyclosporin A and alpha-difluoromethylornithine on the growth of hamster pancreatic cancer in vitro

The growth and survival of hamster H2T pancreatic ductal adenocarcinoma in vitro are known to be significantly reduced by inhibitors of polyamine biosynthesis. alpha-Difluoromethylornithine (alpha-DFMO) is a specific and irreversible inhibitor of ornithine decarboxylase, the rate-limiting enzyme in polyamine biosynthesis. alpha-DFMO treatment inhibits the growth of H2T pancreatic cancer cells and decreases H2T cell survival in vitro and in vivo. In the present study, the effects of cyclosporin A (CsA) were examined on growth, survival, and polyamine levels in H2T pancreatic ductal adenocarcinoma in vitro. CsA had inhibitory effects on H2T pancreatic cancer growth similar to those of alpha-DFMO; these effects were blocked by the addition of the polyamine putrescine. Polyamine levels were found to be significantly altered in cells treated with CsA and/or alpha-DFMO. The combination of CsA (8.3 X 10(-4) mM) and alpha-DFMO (0.5 mM or 1.0 mM) inhibited H2T cell survival to a greater extent than either agent alone. These results suggest that CsA in combination with other agents that inhibit polyamine synthesis may be useful for the treatment of pancreatic cancer.

Catabolism of secretin by the liver and kidney

We have investigated the roles of the liver and the kidney in the catabolism of secretin, using a specific and sensitive radioimmunoassay. Dogs were prepared with sampling catheters in the aorta, hepatic vein, portal vein, and renal vein and with electromagnetic flow probes on the portal vein, hepatic artery, and renal artery. Secretin levels in the vessels entering and leaving the liver and kidney were determined by radioimmunoassay and the total mass of secretin [concentration (picograms per milliliter) X plasma flow rate (milliliter per minute)] was calculated during an intravenous infusion of exogenous secretin and during release of endogenous secretin by acidification of the proximal intestine. The total masses of secretin entering and leaving the liver were the same during secretin infusion and during the release of endogenous secretin. Under conditions of elevation of plasma secretin, however, the kidney extracted 30 percent of arterial secretin during secretin infusion and 45 percent during release of endogenous secretin. Clearly the kidney is a major site of secretin catabolism.

Program evaluation within a health promotion framework

Program evaluation can assist in assessing the conceptualization, design, implementation and utility of health promotion action. Evaluation of health promotion, with multiple strategies combining individual, social and policy action, lends itself to an evaluation-as-politics paradigm. Consideration of the interests of all major stakeholders, use of a series of related studies, and a commitment to multiple methods and multiple perspectives characterize this paradigm. Simple, practical research that is adequate for answering relevant questions is required. The program evaluator is not a neutral, scientific observer--he/she is a participant in the political arena along with other stakeholder groups. A model of the areas of interest in evaluation of health promotion, some potential evaluation questions, and a health promotion impact evaluation model are presented to emphasize unique aspects involved in evaluation of health promotion action. The evaluator can take a proactive role and challenge problems in conception and implementation of health promotion action. He/she can advocate for health promotion.

Bile enhances release of insulin: an incretin-mediated effect

Ingestion of food stimulates secretion of bile and release of gut hormones that enhance nutrient-stimulated release of insulin. The extent of physiologic participation of bile in the enteroinsular axis was examined in seven conscious dogs (weight: 20 +/- 2 kg) that were prepared for study with chronic cannulas placed in the duodenum opposite the ampulla of Vater. On separate days, a meal consisting of 10 gm (MG-10), 25 gm (MG-25), or 62 gm (MG-62) of glucose (dextrose) was given orally in the presence of normal bile flow or during bile diversion. Bile diversion was achieved by catheterization of the common bile duct via the duodenal cannula. The insulin responses (given as ng [0-120] min/ml) to the different glucose meals, with bile present (BP) or absent (BA) in the lumen, were as follows: MG-10, 81 +/- 8 BP and 72 +/- 11 BA; MG-25, 172 +/- 25 BP and 100 +/- 6 BA (p less than 0.05); and MG-62, 390 +/- 79 BP and 153 +/- 32 BA (p less than 0.05). Only MG-25 and MG-62 produced a significant elevation of plasma glucose concentrations. Release of gastrin was not affected by either the presence of bile or the glucose content of the meal. We conclude that endogenous bile enhances nutrient-stimulated release of insulin, this effect is glucose-dependent with a threshold of approximately 1 gm/kg of glucose, and bile may facilitate the release of insulinotropic hormones other than gastrin.

Role of gastrin and gastrin receptors on the growth of a transplantable mouse colon carcinoma (MC-26) in BALB/c mice

We recently reported trophic response of transplantable mouse colon cancer cells (MC-26) to pentagastrin, in vivo, and demonstrated gastrin receptors on MC-26 cells, in vitro. In the present study, growth of MC-26 cells in mice, in response to pentagastrin, was studied in relation to binding kinetics and capacity of gastrin receptor. Gastrin receptor levels on mouse fundic and colonic membranes and on MC-26 cellular membranes were determined before MC-26 cell inoculation and designated as Day 0 levels. Four groups of mice were next inoculated with MC-26 cells and given injections of either pentagastrin (treated) or normal saline (control) for 10 or 15 days. At the end of the treatment periods, body, tumor, fundic, and colon weights were noted and gastrin receptor measured. tumor and fundic weights increased significantly within 15 days of pentagastrin treatment, compared to control values. In control (non-pentagastrin treated) mice, the binding affinity of gastrin receptor on tumor membranes was significantly decreased and associated with the complete loss of high-affinity gastrin receptor (Kd = less than 0.5 nM) by Day 15 of tumor growth. On the other hand, both the binding affinity and gastrin receptor levels of tumor membranes were maintained at Day 0 values by pentagastrin treatment. Endogenous gastrin was therefore ineffective in maintaining high-affinity gastrin receptor on control tumors. A significant number of low-affinity gastrin-binding sites (Kd = less than 2 nM) appeared in control tumors by Day 15, which could reflect rapid dedifferentiation or conformational changes of gastrin receptor in the absence of high levels of normal regulatory hormones. These studies demonstrate that the trophic effects of gastrin on MC-26 cells are probably mediated by its regulation and maintenance of the binding affinity and capacity of gastrin receptor on the cancer cells, in vivo.

Activation of hepatic proliferation-associated transcription factors by lipopolysaccharide

BACKGROUND

The hepatic acute-phase response is the result of reprogramming of gene expression in the liver. Similar acute-phase responses occur in regenerating liver after partial hepatectomy and are preceded by increases in the expression of a set of transcriptional regulatory proteins that are encoded by "immediate-early" genes. The purpose of this study was to determine whether acute systemic inflammation after lipopolysaccharide injection induces hepatic immediate-early genes that are induced by partial hepatectomy.

METHODS

Two- to 4-month-old Balb/c mice received intraperitoneal Escherichia coli lipopolysaccharide (0111:B4; 100 micrograms), and total liver RNA, nuclear protein extracts, or total liver protein lysates were obtained at 0, 1, 3, 12, and 24 hours. RNA blot hybridization analysis was used to determine steady-state messenger RNA levels for c-jun, jun-B, jun-D, c-fos, fos-B, fra-1, nup475, and zif268. Specific nuclear protein-binding activity was determined by gel mobility shift assay. The protein c-Jun was detected by antibody-blocking experiments, and Jun-B was detected by gel supershift assay of the activating protein (AP-1) complex. Steady-state Jun-B levels were determined by immunoblot analysis.

RESULTS

Intraperitoneal injection of lipopolysaccharide is followed by induction (from fivefold to 13-fold) of c-jun, jun-B, c-fos, zif268, and nup475 messenger RNAs in the liver. Lipopolysaccharide induced increases in AP-1 and Zif268 consensus DNA-binding activity in mouse liver. The proteins c-Jun and Jun-B are detected in the AP-1 complex after administration of lipopolysaccharide.

CONCLUSIONS

The induction of hepatic immediate-early genes after lipopolysaccharide is similar to that that follows partial hepatectomy. These transcription factors likely have important roles in the reprogramming of gene expression that leads to the acute-phase response.

Loss of heterozygosity in human primary prostate carcinomas: a possible tumor suppressor gene at 7q31.1

We studied loss of heterozygosity (LOH) on human chromosome 7q to determine the location of a putative tumor suppressor gene (TSG) in human primary prostate carcinomas. Samples were obtained from 16 primary prostate carcinomas surgically removed from patients at The University of Texas M. D. Anderson Cancer Center. Paired normal and tumor DNAs were used as template for PCR amplification of a set of 14 CA microsatellite repeats on 7q21-qter. Twelve of 16 cases studied had LOH at one or more loci on 7q. Eighty-three percent LOH (five of six informative cases) was detected with D7S522 at 7q31.1-7q31.2. Percentage of LOH was normally distributed around D7S522. The high incidence of LOH in primary prostate carcinomas suggests that there is a TSG relevant to the development of prostate cancers at 7q31.1-31.2, confirming our previous functional evidence for a TSG at this location. Further research needs to be conducted to establish the identity and function of this putative TSG.

Behavioral changes in Huntington Disease

OBJECTIVES

This study aimed to gain a better understanding of behavioral abnormalities in Huntington disease (HD) and to develop a method for reliably assessing these changes.

BACKGROUND

Behavioral changes are a central feature of HD and often cause considerable distress and difficulty to patients and their relatives. However, they have received little attention from research despite their prevalence and clinical significance.

METHODS

One hundred thirty-four patients with HD were assessed using the Problem Behaviors Assessment for Huntington Disease (PBA-HD), an instrument for rating the presence, severity and frequency of behavioral abnormalities in HD.

RESULTS

The findings confirm that behavioral problems are common among patients with HD. The most common symptoms were loss of energy and initiative, poor perseverance and quality of work, impaired judgment, poor self-care and emotional blunting. Affective symptoms such as depression, anxiety and irritability occurred in around half the patients studied. Psychotic symptoms (hallucinations and delusions) were rarely reported. Factor analysis distinguished three clusters of behavioral symptoms, which were interpreted respectively as reflecting Apathy, Depression and Irritability. The 'Apathy' factor was highly correlated with duration of illness, whereas no such relationship was observed for the 'Depression' and 'Irritability' factors.

CONCLUSIONS

The results suggest that certain behavioral changes are fundamental to the progression of HD, whereas others have a more complex relationship to the disease process. The findings have implications for the choice of behavioral measures used to evaluate efficacy of therapeutic interventions.