Ischemia and reperfusion in pancreas

Ischemic diseases of heart and brain are the primary causes of mortality in industrialized nations. The ischemic injury with the consecutive reperfusion is responsible for the disturbance of microcirculation with ensuing tissue damage and organ dysfunction. Recent evidence suggests that oxygen-derived free radicals and activated polymorphonuclear leukocytes produced in ischemic tissue are instrumental in the development of ischemic cell injury. In pancreas, ischemia/ reperfusion is proposed as a potentially damaging factor accounting in part for the pathogenesis of acute pancreatitis. Apart from ischemia/reperfusion injury, the kallikrein-kinin system mediates acute inflammation associated with enhanced capillary permeability and accumulation of polymorphonuclear leukocytes, cardinal features of ischemia/reperfusion injury also in acute pancreatitis. Therefore, it seems reasonable to use bradykinin-antagonists to influence postischemic reperfusion injury of the pancreas. In the following, we describe the pathophysiology of ischemia/reperfusion injury with special reference to the pancreatic microcirculation and morphological changes as observed in a model of complete and reversible ischemia. Furthermore, we will discuss the effects of two bradykinin-antagonists (HOE 140 and CP-0597) on functional integrity of the pancreas after ischemia/ reperfusion.

Effects of dextran on microvascular ischemia-reperfusion injury in striated muscle

The objectives of this study were 1) to elucidate the effects of dextran (Dx) at a nonhemodiluting dose of 5 mg/kg on ischemia-reperfusion injury in striated muscle and 2) to investigate whether the effects are dependent on the molecular weight of Dx. We used the model of a 4-h pressure-induced ischemia in the hamster skinfold chamber. By means of intravital microscopy the following parameters were assessed: vessel diameter, red blood cell velocity, rolling and adherent leukocytes, macromolecular extravasation, and functional capillary density. The animals received a continuous infusion (total dose 5 mg/kg) of dextran of different molecular weights or equivalent volumes of saline. Seven groups were studied: NaCl (control, n = 6), Dx 1 (n = 6), Dx 40 (n = 7), Dx 60 (n = 6), Dx 70 (n = 7), Dx 110 (n = 7), and Dx 150 (n = 7). Leukocyte rolling was reduced by all Dx fractions, the difference from the control reaching significance 0.5 h after reperfusion in the Dx 60, Dx 70, and Dx 110 group, whereas leukocyte adherence was attenuated by > 40,000-mol-wt Dx at 0.5 h after reperfusion. Concomitantly, functional capillary density tended to improve after treatment with > or = 40,000-mol-wt Dx. However, all Dx fractions studied failed to reduce postischemic macromolecular extravasation. These results provide evidence that Dx at 5 mg/kg attenuates postischemic microvascular disturbances; this effect is molecular weight dependent.

Skeletal muscle microvascular and tissue injury after varying durations of ischemia

The purpose of this study was to examine the effect of varying durations of ischemia on several microvascular parameters in the awake hamster chamber model. The goal was to characterize the microvascular damage that occurs in skeletal muscle as a result of ischemia and reperfusion. The chamber tissues were subjected to 1-5 h of ischemia, and then the following parameters were measured: vessel diameter, endothelial thickness, macromolecular leakage, red blood cell velocity, adherent leukocytes, rolling leukocytes, freely flowing leukocytes, functional capillary density, and propidium iodide-positive cell nuclei. In control animals there was no significant difference in any parameters over the entire observation period. After 1 or 2 h of ischemia an increase in rolling and adherent leukocytes was measured. After 3 h of ischemia there was a significant increase in the mean endothelial thickness and in the number of nonviable cells. After 4 h of ischemia a significant difference in the extent of macromolecular leakage and the functional capillary density was additionally observed. After 5 h of ischemia this damage was more pronounced and often so severe that approximately 50% of the vessels demonstrated no reflow.

Effects of leukocyte capillary plugging in skeletal muscle ischemia-reperfusion injury

The purpose of this study was to examine the relationship between increased capillary network resistance due to leukocyte capillary plugging and tissue injury following ischemia-reperfusion (I/R). After a 30-min complete ischemia in rat spinotrapezius muscle, the frequency and duration of leukocyte capillary plugging were measured throughout capillary networks and used to estimate the increase in network flow resistance for I/R alone, I/R with phalloidin (Pl), and I/R with both Pl and cytochalasin D. Propidium iodide (PI) was used to label nonviable muscle cell nuclei within the volume of tissue supplied by the capillary network, and counts were made before ischemia, immediately after reperfusion, and 1 h postreperfusion. For I/R alone and I/R + Pl there is a linear correlation between the increase in resistance (up to 29%) and the increase in the number of PI-positive nuclei during the reperfusion period. With both Pl and cytochalasin D present in the superfusate, the resistance increase was abolished and the amount of tissue damage during reperfusion was minimized. The results indicate that the increase in resistance is linearly related to the tissue damage and that a reduction of the leukocyte stiffness reduces the injury.

The presence of rheumatoid factor in sera from anti-HCV positive blood donors interferes with the detection of HCV-specific IgM. Trent HCV Study Group

BACKGROUND/AIMS

IgM anti-HCV has been reported as a useful marker of disease activity and of likely response to interferon therapy in patients with chronic hepatitis C virus infection. Sera from patients with hepatitis C virus infection may contain rheumatoid factor. This study was designed to investigate the possible effect of rheumatoid factor in an IgM anti-HCV assay.

METHODS

Sera from 75 blood donors with chronic hepatitis C virus infection were tested for the presence of IgM anti-HCV using a core-derived peptide as antigen, before and after removal of IgG. These sera and appropriate control sera were also tested for the presence of rheumatoid factor.

RESULTS

Removal of IgG prior to IgM testing resulted in a significant loss of reactivity in the IgM anti-HCV assay in 30/41 sera that were positive in this assay when tested untreated. Seventy per cent of anti-HCV positive sera were also positive for rheumatoid factor.

CONCLUSIONS

Rheumatoid factor causes significant false positive reactivity in IgM anti-HCV detection assays. The results of assays that do not account for this interference should be viewed with caution.

Clinical improvement of photoaged skin with 50% glycolic acid. A double-blind vehicle-controlled study

BACKGROUND

Although there is increasing interest in the use of glycolic acid in the treatment of photoaged skin, to our knowledge, no controlled study has been done to assess the efficacy or the mode of this agent.

OBJECTIVE

The purpose of this study was to determine whether 50% glycolic acid can improve photoaged skin and to study the histological basis for this improvement.

METHODS

Forty-one volunteers were recruited into this double-blind vehicle-controlled study. Glycolic acid (50%) or vehicle was applied topically for 5 minutes to one side of the face, forearms, and hands, once weekly for 4 weeks. Punch biopsies were taken at pretherapy and at 5 weeks for histologic study.

RESULTS

Significant improvement noted included decrease in rough texture and fine wrinkling, fewer solar keratoses, and a slight lightening of solar lentigines. Histology showed thinning of the stratum corneum, granular layer enhancement, and epidermal thickening. Some specimens showed an increase in collagen thickness in the dermis.

CONCLUSION

The results of this study demonstrate that the application of 50% glycolic acid peels improves mild photoaging of the skin.

Pyoderma gangrenosum with hepatopancreatic manifestations in a patient with rheumatoid arthritis

Pyoderma gangrenosum is a dermatological disease of unknown origin. We report the case of a 47-year-old woman with cutaneous lesions of pyoderma gangrenosum associated with hepaticopancreatic involvement. We found no other similar cases in the literature. The outcome was favorable with steroid therapy. She was free of symptoms after one year.

In vivo responsiveness of morphological variants of growth hormone-producing pituitary adenomas to octreotide

The somatostatin analog, octreotide, is an inhibitor of growth hormone (GH) secretion that has been used to treat patients with GH-producing pituitary tumors. In this study we investigated the in vivo responsiveness to treatment with this analog in patients harboring different morphological types of GH-producing pituitary adenomas. Both GH and insulin-like growth factor I (IGF-I) plasma levels in 30 patients treated with octreotide (300 micrograms/day) for 4 months preoperatively were compared with those from 30 patients who did not receive treatment preoperatively. Tissue samples were studied using ultrastructural and immunohistochemical techniques. Amongst patients harboring densely granulated (DG) adenomas, mean GH levels were reduced to 32 +/- 9% by octreotide, to 30 +/- 7% by surgery and to 26 +/- 9% of baseline by both interventions. Surgery was equally as effective in lowering GH levels in patients with sparsely granulated (SG) adenomas as it was in those with DG adenomas; in patients with SG adenomas, GH levels were reduced by surgery alone to 37 +/- 16% and to 24 +/- 15% when performed following octreotide pretreatment. In contrast, treatment with octreotide alone in patients harbouring SG adenomas reduced GH levels to only 70 +/- 13% of baseline (p < 0.02 compared to surgery alone, or surgery and octreotide). We conclude that the GH inhibitory effects of octreotide are significantly better in patients harboring DG somatotroph adenomas compared with those harboring SG adenomas.

The impact of continuous subcutaneous infusion of octreotide on gallstone formation in acromegalic patients

Treatment of acromegaly with intermittent sc injections of octreotide is associated with an increased incidence of cholelithiasis. We investigated the incidence of gallstone formation, the occurrence of gallbladder disease, and the response of gallstones to ursodeoxycholic acid in 30 acromegalic patients who were treated with a continuous sc infusion of octreotide at doses between 200 and 800 micrograms/day for 3-70 months. Of the 30 patients, 28 had pretretment ultrasonography of the biliary tree performed, and all had frequent follow-ups. Nine patients underwent pre- and posttreatment bile sampling. No patient treated for less than 6 months and 18.5% of patients treated for more than 6 months developed new gallstones. No patient developed symptomatic cholelithiasis while receiving octreotide therapy. Of six patients who developed gallstones, four were treated with ursodeoxycholic acid, which dissolved all gallstones. One patient with gallstones experienced an episode of biliary colic when octreotide was withdrawn; however, no cholecystitis was found at subsequent cholecystectomy. Bile sampling showed that 8 (75%) of the 12 patients who were assessed demonstrated microcrystals, whereas in 3 (50%) of 6 patients who were closely analyzed thereafter, microcrystals disappeared once octreotide therapy was stopped. Our results show that continuous sc infusion octreotide therapy increases the incidence of cholelithiasis over normal values, as is the case with intermittent sc injections. Although higher octreotide levels are sustained with continuous sc infusion, this is not associated with an increased risk of gallstone formation compared with intermittent sc octreotide therapy.

Octreotide treatment of carcinoid syndrome: analysis of published dose-titration data

BACKGROUND

Octreotide has proven therapeutically effective in carcinoid syndrome, but the rarity of carcinoid tumors has hampered detailed dose-ranging studies. This study analysed published dose-titration data on octreotide use in carcinoid patients to (a) investigate the relation between octreotide dose and efficacy and (b) establish octreotide dosing recommendations for maximum therapeutic benefit.

METHOD

An exhaustive, computer-assisted literature search for published articles employing octreotide to manage patients with carcinoid syndrome was performed using several databases. The relation between octreotide dose and efficacy in decreasing urinary 5-hydroxyindoleacetic acid (5-HIAA) levels, flushing and diarrhoea was analysed for seven dose ranges by pooling data from selected articles.

RESULTS

Analysis of data compiled from 62 published studies revealed that maximum effective therapeutic doses of octreotide effectively controlled symptoms in up to 93% of patients, and that increasing the dose of octreotide is associated with increased benefit with respect to control of flushing, diarrhoea and 5-HIAA levels.

CONCLUSIONS

We recommend starting octreotide therapy at 100 micrograms subcutaneously t.d.s. in patients with mild/moderate, non-life-threatening carcinoid syndrome. Since therapeutic response to octreotide varies markedly among patients, we recommend titrating the octreotide dose in increments of 50-100 micrograms every 8 h until adequate symptom control is achieved.

Consensus statement: octreotide dose titration in secretory diarrhea. Diarrhea Management Consensus Development Panel

Octreotide is an effective therapeutic option in controlling secretory diarrhea of varied etiology. However, marked patient-to-patient differences in the antidiarrheal effects necessitate titration of octreotide dose in individual patients to achieve optimal symptom control. A consensus development panel established guidelines for octreotide dose titration in patients with secretory diarrhea. Overall, the panel recommended an aggressive approach in selecting the initial octreotide dose and in making subsequent dose escalations in patients with secretory diarrhea due to gastrointestinal tumors (eg, carcinoids, VIPomas), AIDS, dumping syndrome, short bowel syndrome, radiotherapy, or chemotherapy. To avoid hypoglycemia in patients with diabetes mellitus-associated secretory diarrhea, the panel recommended a low initial octreotide dose and a conservative titration regimen with close monitoring a blood glucose levels. The end point of therapy should focus on a reduction in diarrhea (frequency of bowel movements or stool volume) rather than normalization of hormonal profile. Overall, octreotide is well tolerated; principal side effects are transient injection site pain and gastrointestinal discomfort. For many patients with secretory diarrhea, octreotide therapy is expected to improve the overall health and quality of life and in the long run will lessen health care costs.

A prospective multicenter octreotide dose response study in the treatment of acromegaly

The somatostatin analog octreotide has proven to be an effective form of treatment for various hypersecretory states including acromegaly. This report describes the effects of escalating doses of octreotide on the growth hormone (GH) profiles, insulin-like growth factor-1 (IGF-1), prolactin (PRL), and adverse effects in 99 patients with acromegaly. Treatment with octreotide was initiated at 50 micrograms sc every 8 h and the dose gradually titrated to a maximum of 1500 micrograms/d if more than 75% of GH determinations in a 12-h day profile were above detection limits. This dose was maintained for the duration of 6 months. Seventy-three percent of patients did not reach the GH reduction criterion at the 300 micrograms dose. Mean GH levels decreased from 33 +/- 4 micrograms/l to 10 +/- 1 microgram/l (p < 0.001) while receiving the 300 micrograms/d dose. The percentage decrease in mean GH levels, however, was dose-independent reaching 50 +/- 5% of baseline with 300 micrograms/d, 55 +/- 5% with 600 micrograms/d, 57 +/- 6% with 900 micrograms/d, and 56 +/- 5% with 1500 micrograms/d. Maximal GH suppression, however, was achieved in 40%, 17%, 7%, and 16% of subjects by the 300 micrograms, 600 mg, 900 micrograms, and 1500 micrograms doses respectively. GH suppression was independent of duration of treatment. While there was a tendency for a greater degree of IGF-1 reduction with the higher doses, the rate of normalization (30-37%) was not influenced by the dose of octreotide administered. Elevated PRL levels also declined with the use of higher doses of octreotide.(ABSTRACT TRUNCATED AT 250 WORDS)

Kinetics of white blood cell staining by intravascular administration of rhodamine 6G

Rhodamine 6G is a vital dye accumulating in the mitochondria of cells. It is used in intravital fluorescence microscopy for contrast enhancement of white blood cells (WBC), enabling visualization of WBC in the microvasculature even at high center flow velocity. The aim of this study was to examine the kinetics of WBC staining after intravascular administration of rhodamine 6G in Lewis rats, Syrian golden hamsters and BALB/c mice. For this purpose, WBC were isolated from whole blood and the percentage of cells stained positively as well as their fluorescence intensity were measured by flow cytometry 5, 15, 30 and 60 min after dye administration. Injection of 0.06-0.2 mg/kg body weight of rhodamine 6G resulted in staining practically all granulocytes and monocytes over the entire observation period of 60 min. Fluorescence intensity of WBC was adequate to be detected in an experimental setup for intravital fluorescence microscopy in the hamster dorsal skinfold chamber. The degree of WBC staining was different in the species studied, yielding a higher percentage of stained lymphocytes in rats than in mice and hamsters. Staining of lymphocytes declined within 60 min after rhodamine application, the loss of fluorescent label being most pronounced in hamster cells. After 15-30 min, relative fluorescence intensity of stained lymphocytes had decreased considerably, indicating the need for reinjection of the dye or limiting microscopic analysis to approximately 15 min after rhodamine 6G administration. While the intravascular injection of rhodamine 6G results in adequate staining of granulocytes and monocytes, only a fraction of lymphoid cells are stained.

Continuous versus intermittent subcutaneous infusion of octreotide in the treatment of acromegaly

This review evaluates the efficacy, tolerability, and safety of continuous subcutaneous infusion (CSI) relative to intermittent subcutaneous injection (ISI) of the somatostatin analog, octreotide in the treatment of acromegaly. Data was extracted from five clinical series using CSI octreotide in acromegaly, six reports comparing CSI to ISI, and three studies comparing pulsatile subcutaneous infusion (PSI) to ISI. Effects of each drug regimen on the control of growth hormone (GH), insulin-like growth factor (IGF-1), clinical symptomatology, pituitary tumor size, and adverse effects were evaluated. Normalization of serum GH or IGF-1 levels, as well as improvement in clinical symptoms was reported in the majority of the patients studied. Cases in which pituitary adenomas decreased in size were also documented during the study period. When the effects of CSI were compared with ISI, a more pronounced control of GH and IGF-1 was observed. In addition, diurnal GH fluctuation during CSI was significantly reduced relative to ISI in two reports. Moreover, in two patients, CSI achieved similar clinical and biochemical effects at lower doses than when the drug was given by ISI. Finally, adverse effects with CSI may be less severe than with ISI. Continuous subcutaneous infusion of octreotide produced biochemical improvement in 67 of the 88 patients reviewed. When compared with ISI, CSI induced more pronounced biochemical control, often with less fluctuation in GH and IGF-1 levels. Because of a lack of data, definite conclusions regarding the differences between regimens on clinical symptomatology and tolerability could not be discerned. A large prospective, long-term randomized crossover study is recommended to make these determinations.

Effects of octreotide on biliary lipid composition and occurrence of cholesterol crystals in patients with acromegaly. A prospective study

Treatment with the somatostatin analog octreotide is associated with increased gallstone formation. The mechanism of formation of these stones is unclear. The purpose of this study was to examine the effect of a three-month treatment with octreotide on biliary lipid composition and the occurrence of cholesterol crystals in patients with acromegaly. Thirteen patients with active acromegaly, aged 24-76 years, received octreotide (100 micrograms three times daily) for three months. Fasting gallbladder bile was obtained during upper gastrointestinal endoscopy after ceruletide stimulation. Bile was studied before and at the end of the treatment period (N = 7), only before (N = 4), or only at the end of treatment (N = 2). Before treatment, all bile samples but one were supersaturated with cholesterol. However, none contained cholesterol crystals on microscopic examination. At the end of the treatment period, all but two samples were supersaturated with cholesterol. Three of nine samples contained cholesterol crystals, a proportion significantly higher than before treatment. The relative proportions of bile acids, cholesterol, and phospholipids, and the mean cholesterol saturation index were not different before and during treatment. Follow-up ultrasonography showed the occurrence of gallstones in four patients, including the three patients who had cholesterol crystals. We conclude that: (1) fasting gallbladder bile of patients with acromegaly is frequently supersaturated with cholesterol; (2) treatment with octreotide does not increase cholesterol saturation index, but may induce the occurrence of cholesterol crystals. The data are consistent with the view that gallstones induced by octreotide are cholesterol stones and suggest that the drug may impair gallbladder motility and/or decrease cholesterol nucleation time.

Acromegaly. Clinical and biochemical features in 500 patients

This prospective study defines the clinical and biochemical features of acromegaly in a large cohort of patients. There was no difference in sex distribution, and for men and women the mean ages at diagnosis (40 +/- 12 and 40 +/- 14 yr, respectively) were similar. Nearly three-quarters of patients were overweight and some 12% severely overweight; the frequency and severity of obesity also was not different between the sexes. Half of patients were hypertensive or were taking anti-hypertensive drugs. Neither GH nor insulin levels were significantly different between normotensive and hypertensive patients. Acral growth and facial coarsening, soft tissue swelling, and excessive perspiration were present in the majority (98%) of patients. Mean serum GH, Sm-C, and PRL levels did not differ between the sexes. Sm-C levels correlated with mean GH concentration (r = 0.31, p < 0.001), both variables inversely related to age. With each decade of life, mean GH and Sm-C levels declined by 7.6 +/- 0.2 ng/mL and 0.5 +/- 0.2 U/mL, respectively. Impaired glucose tolerance was diagnosed in 36% and frank diabetes mellitus in 30% of patients. Hyperprolactinemia was noted in 18% of patients. Galactorrhea was noted in 43 (9%) patients, most of whom were female; the mean GH levels of patients with galactorrhea (60.1 +/- 13 ng/mL) were higher than those of patients without (35.4 +/- 2.6 ng/mL, p = 0.02). Acromegaly appears to afflict men and women equally with a preponderance of presentation in the fourth decade of life.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphological effects of octreotide on growth hormone-producing pituitary adenomas

The SRIH analog octreotide is a potent GH-inhibiting agent that has been used to effectively treat patients with acromegaly. To investigate the morphological changes induced by octreotide on GH-producing pituitary tumors, we examined 86 adenomas from acromegalic patients who participated in a multicenter study. GH- producing pituitary adenomas removed from 43 patients treated preoperatively with octreotide for 4 months were compared to those obtained from 43 untreated acromegalic patients. Tissue samples were studied by histology, immunohistochemistry, and transmission electron microscopy as well as light microscopic and ultrastructural morphometry. The morphological appearance of some tumors was unaltered by octreotide treatment. Necrotic changes were not apparent in any. Acidophilia and GH immunoreactivity were more pronounced in the octreotide-treated tumors. Perivascular and interstitial fibrosis was more prevalent in the octreotide group (72% vs. 42%). An increase in hormone granularity was obvious in 4 of 15 densely granulated and 2 of 9 sparsely granulated (SG) tumors from treated patients. A decrease in cell size was conspicuous in 4 of 15 densely granulated and 2 of 10 SG adenomas. There was a slight downward trend in the cell and cytoplasmic size in all treated tumors and a slight upward trend in secretory granule size in treated SG adenomas. Only 2 of 9 SG adenomas in the octreotide group, however, demonstrated a statistically significant reduction in cell and cytoplasmic size. There was no statistically significant change in the size of nuclei, secretory granules, or lysosomes between the 2 groups. Decreased cell size and increased granularity were not linked, however. We conclude that there are no striking morphological alterations in GH pituitary adenomas that can be consistently associated with octreotide treatment.

Effect of octreotide on glucose tolerance in acromegaly

To determine the effect of the somatostatin analog octreotide on glucose tolerance in acromegaly, we examined glucose profiles, oral glucose tolerance and the insulinogenic index in patients treated with this analog. Ninety patients participated in a long-term, prospective, open-label study. There was no significant change between mean daily blood glucose profiles at baseline or during octreotide treatment. Using glucose tolerance test criteria, 61% of 90 patients had normal baseline glucose tolerance. While on octreotide, 20% and 29% of these patients, respectively, developed impaired glucose tolerance or became frankly diabetic. Conversely, three of the patients who were diabetic at baseline (N = 11) became normal (18%) or developed impaired glucose tolerance (9%) during octreotide therapy. There was no relationship between the dose of octreotide and change in glycemic state. The insulinogenic index (insulin/glucose) response to a glucose challenge decreased uniformly in octreotide-treated patients. Female patients and those with elevated baseline insulin levels were more likely to develop diabetes mellitus during octreotide therapy. In conclusion, octreotide significantly alters glucose tolerance in patients with acromegaly, mandating glucose monitoring during this form of therapy.

Leukocyte-capillary plugging and network resistance are increased in skeletal muscle of rats with streptozotocin-induced hyperglycemia

Although diabetic retinopathy is a leading cause of blindness, the mechanisms underlying the disorder remain unresolved. Recent studies have reported both an increase in viscosity and a decrease in filterability of blood in diabetes, as well as increased activation of monocytes and granulocytes. These rheological effects have been implicated in capillary closure which is an early pathological change in diabetic retinopathy. The objective of this study was to quantitatively measure in vivo for the first time the resistance increase in capillary networks due to leukocyte-capillary plugging during experimental diabetes. Intravital measurements of plugging durations and frequencies were made throughout capillary networks in the spinotrapezius muscle of anesthetized rats subject to streptozotocin (STZ) induced hyperglycemia. These data were used to estimate the increase in microvascular flow resistance due to leukocyte plugging. The increase averaged 13.0% which is significantly different (p < 0.05) from the 1.1% observed in previous experiments with normal rats. Although the total white cell count was normal, the diabetic animals exhibited a significantly increased percentage of monocytes. A small but significant decrease in capillary diameter in the diabetic animals was also observed. Thus, leukocytes have a significant impact on microvascular hemodynamics in diabetic animals, and leukocyte-capillary plugging may be an important mechanism of capillary closure and subsequent microvascular dysfunction in diabetic retinopathy.