Amplification and expression of the cyclin D1 gene in anal and esophageal squamous cell carcinomas

Cyclin D1 is a cell-cycle regulator and candidate proto-oncogene implicated in the pathogenesis of numerous tumor types. Amplification of the cyclin D1 gene occurs commonly in esophageal squamous cell carcinomas. However, no studies have examined the role of cyclin D1 in anal carcinogenesis. We examined 20 esophageal squamous cell carcinomas and 24 anal carcinomas for cyclin D1 alterations. Protein expression was evaluated by immunohistochemistry using the cyclin DIGM antibody (Novocastra, Newcastle upon Tyne, UK). Cyclin D1 amplification was examined by fluorescent in situ hybridization (FISH), using a cyclin D1 probe obtained from Toshiya Inaba at St. Jude Children's Research Hospital, Memphis, TN. The FISH sections were analyzed using a Leica (Deerfield, IL) confocal microscope. By immunohistochemistry, 75% of esophageal carcinomas showed evidence of cyclin D1 expression. Cyclin D1 amplification was detected by FISH in 65% of esophageal cancers. There was good correlation between cyclin D1 protein expression and gene amplification, although some tumors showed protein overexpression in the absence of gene amplification. Among the 24 anal carcinomas studied, 8% showed weak cyclin D1 immunoreactivity in rare tumor cells. None of the anal tumors showed cyclin D1 amplification. We conclude that cyclin D1 alterations are common in esophageal carcinomas but do not appear to be important in anal carcinogenesis. Immunohistochemical detection of cyclin D1 protein overexpression is a good predictor of cyclin D1 amplification.

Renal cysts and cystic neoplasms

This article reviews the imaging approach to cystic renal lesions. Imaging characteristics of lesions ranging from simple cysts to cystic renal cell carcinomas are discussed. The MR appearance of cystic renal masses is described and the role of MR imaging in the evaluation of these lesions is discussed.

Effects of the program-management model: a case study on professional rehabilitation nursing

In an attempt to increase organizational innovation and flexibility, Cardinal Hill Rehabilitation Hospital moved from the traditional discipline-management model to the program-management model. In the restructuring, the integrity of professional nursing practices was put to the test when the director of nursing position and numerous staff nursing positions were eliminated. This article evaluates statistics from the three years that have elapsed since the restructuring event in order to determine the new program-management model's compatibility with patient outcomes associated with professional nursing standards.

Comparison of scintigraphy and lactulose breath hydrogen test for assessment of orocecal transit: lactulose accelerates small bowel transit

The lactulose breath test (LBT) and gastroenterocolonic scintigraphy (GECS) can both be used to measure orocecal transit time (OCTT). The aims of this study were (1) to measure OCTT by LBT and GECS and (2) to determine whether lactulose alters orocecal transit.

METHODS

Eight normal subjects underwent simultaneous breath hydrogen testing, GECS, and duodenal manometry while receiving either 10 g lactulose or placebo with a radiolabeled solid/liquid test meal during two studies. There was a good correlation between OCTT by LBT and GECS when performed simultaneously (r = 0.95; P < 0.001). OCTT by GECS with lactulose was significantly faster (P = 0.004) than by GECS without lactulose, despite no change in gastric emptying of liquids and slowing of gastric emptying of solids (P = 0.02). The postprandial duodenal motility index was greater with lactulose than with placebo (P = 0.031). This study demonstrates that LBT and GECS (without lactulose) are not equivalent measures of OCTT. The standard LBT accelerates OCTT and slows gastric emptying. Therefore, lactulose has a direct accelerating effect on small intestinal transit.

A complete mechanism for steady-state oxidation of yeast cytochrome c by yeast cytochrome c peroxidase

Steady-state oxidation of yeast cytochrome c (yCc) was monitored as a function of ionic strength (mu) for mutants of a cloned cytochrome c peroxidase [CcP(MI)]. The data are best interpreted in the context of a two binding site model, where the affinity of the two sites for yCc differs by approximately 1000-fold and rapid intracomplex electron transfer (ET) occurs only at the high-affinity site identified in the crystal structure. At low mu, catalysis is apparently limited by the rate of yCc dissociation from the reactive high-affinity site (koff). Binding of yCc at the low-affinity site increases koff and therefore increases the rate of catalysis. Mutations at the high-affinity site also increase the rate of catalysis by the 1:1 CcP(MI):yCc complex by increasing koff. Mutations at residues that interact strongly with yCc at the high-affinity site (Asp 34, Glu 290, and Ala 193) cause the greatest increase in koff (25-38-fold at mu = 20 mM). Mutations at residues that interact less strongly with yCc (Glu 32 and Glu 291) cause smaller increases in koff (10- and 3-fold, respectively, at mu = 20 mM). The results provide additional evidence that the high-affinity site formed in solution is similar to the one identified in the crystal structure and that yCc dissociation from this site limits enzyme turnover at low ionic strength. Numerical integration simulations show that the model accurately predicts enzyme turnover rates at the high-affinity site, using published rate constants for the elementary reaction steps.

Development of mupirocin resistance among methicillin-resistant Staphylococcus aureus after widespread use of nasal mupirocin ointment

All methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from colonized or infected patients in a 625-bed public teaching hospital during an epidemic, and for 3 years thereafter, underwent susceptibility testing to mupirocin. Mupirocin resistance among MRSA increased markedly over this period (1990, 2.7%; 1991, 8.0%; 1992, 61.5%; 1993, 65%) in association with increased use of mupirocin ointment as an adjunct to infection control measures.

Plasma membrane phosphotyrosine, Her2-NEU, and epidermal growth factor receptor in human breast cancer. A comparative study

Experimental therapeutic regimens for breast cancer include strategies to block the activity of specific oncogenes. Because oncogenesis is a multistep process, specific oncogenes may drive tumor production at one stage yet not function in another. Since the effectiveness of therapy targeted against oncogenes depends on their function in the tumor, correlation of oncogene function to specific stages of tumor development has therapeutic implications. Among the oncogenes known to be important in breast cancer production are two cell surface growth factor receptors, epidermal growth factor receptor (EGFR) and Her2-NEU (NEU). These proteins are receptor tyrosine kinases that autophosphorylate specific tyrosine residues on activation. The oncogenic potential of these receptors depends on this autophosphorylation. We examined 86 primary formalin-fixed, paraffin-embedded breast tumors for overexpression of EGFR and NEU and correlated our findings with the presence of cell surface phosphotyrosine as an indicator of tyrosine kinase activity at the plasma membrane. Our data indicate that only 34% of tumors that overexpress EGFR or NEU show plasma membrane phosphotyrosine, indicating that in the majority of these tumors, the overexpressed oncogene may not be active at this stage.

The pattern of cell proliferation in neoplastic and nonneoplastic lesions of ulcerative colitis

BACKGROUND

Ulcerative colitis (UC) is a chronic inflammatory disease of the colon characterized by repeated episodes of inflammation and epithelial regeneration. Patients with long-standing UC have an increased risk for the development of dysplasia and subsequent colon carcinoma. Because dysplasia likely results from deregulatec cell proliferation, the authors examined Ki-67 immunoreactivity in tissues from UC patients to examine patterns of proliferation in neoplastic and nonneoplastic lesions.

METHODS

One hundred and eighty-seven specimens were obtained from 41 patients with UC and each lesion evaluated according to the International Classification for Dysplasia in Inflammatory Bowel Disease. All sections were stained with a monoclonal antibody directed against the proliferation marker Ki-67, and evaluated by three observers.

RESULTS

Statistically significant differences in the pattern of Ki-67 immunoreactivity were observed between nonneoplastic and neoplastic lesions. In regenerative mucosa, Ki-67 immunoreactivity localized to the bases of the crypts, and the proliferative zone appeared expanded. In dysplasia, Ki-67 staining was prominent in cells in the superficial mucosa, as well as in cells at the crypt bases. In some dysplasias and all invasive carcinomas, Ki-67 staining was diffusely distributed throughout the crypts, suggesting complete deregulation of normal cell proliferation.

CONCLUSIONS

Cell proliferation is markedly increased in patients with UC, and appears abnormally regulated in neoplastic lesions. Furthermore, Ki-67 staining helps delineate areas of dysplasia in cases in which the distinction from regenerative mucosa is unclear. The increased cell proliferation that occurs in patients with UC may predispose the mucosa to mutational events, thereby increasing cancer risk in these patients.

Design of a ruthenium-cytochrome c derivative to measure electron transfer to the radical cation and oxyferryl heme in cytochrome c peroxidase

A new ruthenium-labeled cytochrome c derivative was designed to measure the actual rate of electron transfer to the Trp-191 radical cation and the oxyferryl heme in cytochrome c peroxidase compound I {CMPI(FeIV = O,R.+)}. The H39C,C102T variant of yeast iso-1-cytochrome c was labeled at the single cysteine residue with a tris (bipyridyl)ruthenium(II) reagent to form Ru-39-Cc. This derivative has the same reactivity with CMPI as native yCc measured by stopped-flow spectroscopy, indicating that the ruthenium group does not interfere with the interaction between the two proteins. Laser excitation of the 1:1 Ru-39-Cc-CMPI complex in low ionic strength buffer (2 mM phosphate, pH 7) resulted in electron transfer from RuII* to heme c FeIII with a rate constant of 5 x 10(5) s-1, followed by electron transfer from heme c Fe II to the Trp-191 indolyl radical cation in CMPI(FeIV = O,R*+) with a rate constant of k(eta) = 2 x 10(6) s-1. A subsequent laser flash led to electron transfer from heme c to the oxyferryl heme in CMPII-(FeIV = O,R) with a rate constant of k(etb) = 5000 s-1. The location of the binding domain was determined using a series of surface charge mutants of CcP. The mutations D34N, E290N, and A193F each decreased the values of k(eta) and k(etb) by 2-4-fold, consistent with the use of the binding domain identified in the crystal structure of the yCc-CcP complex for reduction of both redox centers [Pelletier, H., & Kraut, J. (1992) Science 258, 1748-1755]. A mechanism is proposed for reduction of the oxyferryl heme in which internal electron transfer in CMPII(FeIV = O,R) leads to the regeneration of the radical cation in CMPII-(FeIII,R*+), which is then reduced by yCcII. Thus, both steps in the complete reduction of CMPI involve electron transfer from yCcII to the Trp-191 radical cation using the same binding site and pathway. Comparison of the rate constant k(eta) with theoretical predictions indicate that the electron transfer pathway identified in the crystalline yCc-CcP complex is very efficient. Stopped-flow studies indicate that native yCcII initially reduces the Trp-191 radical cation in CMPI with a second-order rate constant ka, which increases from 1.8 x 10(8) M-1 s-1 at 310 mM ionic strength to > 3 x 10(9) M-1 s-1 at ionic strengths below 100 mM. A second molecule of yCcII then reduces the oxyferryl heme in CMPII with a second-order rate constant kb which increases from 2.7 x 10(7) M-1 s-1 at 310 mM ionic strength to 2.5 x 10(8) M-1 s-1 at 160 mM ionic strength. As the ionic strength is decreased below 100 mM the rate constant for reduction of the oxyferryl heme becomes progressively slower as the reaction is limited by release of the product yCcIII from the yCcIII-CMPII complex. Both ruthenium photoreduction studies and stopped-flow studies demonstrate that the Trp-191 radical cation is the initial site of reduction in CMPI under all conditions of ionic strength.

Vascularity of proliferative breast disease and carcinoma in situ correlates with histological features

The level of vascularity within an invasive breast carcinoma is a predictor of metastatic potential and survival. However, little is known about the vascular potential and prognostic value of angiogenesis in preinvasive breast pathology. Women with proliferative breast disease or carcinoma in situ are at increased risk of developing invasive breast cancer. This relative risk increases in correlation with defined histopathological features. We asked whether these early proliferative lesions and carcinoma in situ were capable of inducing a vascular supply. Vascularity in preinvasive archival paraffin-embedded breast tissue from 90 patients was quantified by immunohistochemical identification of vessels using anti-von Willebrand factor. Vascular scores were analyzed with respect to histopathological diagnosis, age at diagnosis, and presence of coincident invasive disease. These data indicate that: (a) the vascularity of histopathologically normal epithelium is greater in breasts containing invasive disease than in breasts lacking invasive disease; (b) simple proliferative breast disease induces a vascular supply greater than that of normal breast epithelium; and (c) vascularity increases in proportion to epithelial lesion progression and relative risk of invasion. These studies indicate that the vascularity of preinvasive breast pathology may be a clinically useful predictor of invasive breast cancer.

Protective immunity to Listeria monocytogenes elicited by immunization with heat-killed Listeria and IL-12. Potential mechanism of IL-12 adjuvanticity

The results presented here demonstrate the striking potentiating effects of IL-12 when it is combined with listerial immunogens. Although HKLM alone does not elicit strong T-cell responses, the results presented here demonstrate that the combination of HKLM and IL-12 elicited vigorous Listeria-specific Th1-type T-cell responses when administered intraperitoneally. The intensity of these responses, as well as the cytokine profiles of the Listeria-specific peritoneal T cells and macrophages, was remarkably similar to that of Listeria-infected/immune mice. These studies also revealed that typically nonimmunogenic forms of soluble listerial antigen preparations (cLLO, SLP) and LLO peptide homologs (M. A. Miller et al., manuscript in preparation) elicited intense Listeria-specific T-cell responses when administered with IL-12. In conjunction with the generation of specific T-cell responses following injection of IL-12 in combination with either killed Listeria or soluble listerial antigen preparations, macrophages from these mice expressed upregulated quantities of class II MHC and produced increased amounts of IL-12 following restimulation in vitro. Protection studies established that the Listeria-specific T-cell responses elicited by the HKLM + IL-12 mixture conferred protective immunity of mice to a lethal dose of viable L. monocytogenes. Studies designed to investigate the regulation of IL-12 production by peritoneal macrophages revealed that activated macrophages are particularly sensitive to bacterial products. However, nonviable or replication-incompetent bacteria or bacterial products injected alone were unable to influence the ability of macrophages to produce IL-12. The ability of activated macrophages to respond to HKLM was dramatically upregulated upon addition of IFN-gamma and markedly downregulated in the presence of the Th2 cytokines, IL-4 and IL-10. In light of what is known about the ability of IL-12 to induce IFN-gamma production by NK cells and gamma delta T cells, these results suggest that the exogenous addition of IL-12 may help initiate a cytokine cascade which enables the immune system to interact productively with an antigen that is typically nonimmunogenic when administered alone. These findings demonstrate that IL-12 may prove to be a powerful and broadly useful adjuvant component of particulate and soluble antigen-based vaccines directed towards many types of intracellular pathogenic microorganisms. Studies aimed at determining the generality of these findings in other infectious disease models as well as experiments designed to further elucidate the mechanism(s) of IL-12 adjuvanticity are continuing.

Tuberculosis risk after exposure on airplanes

SETTING

Domestic and international air-flights.

OBJECTIVE

To estimate the risk of tuberculosis (TB) transmission aboard aircraft.

DESIGN

A contact investigation of passengers and crew from two flights was conducted following identification of a fellow passenger with pulmonary TB. Immediate post-exposure and follow-up tuberculin skin tests (TSTs) were obtained.

RESULTS

Of 120 contacts, 86 (72%) had a negative TST (< 5 mm); 29 (24%) a positive TST (> or = 5 mm), and 5 (4%) a TST conversion. Of the 29 persons with a positive TST, 27 had other identified risk factors for TB. Risk factors for positive TST included non-US birth (Relative Risk (RR) 9.7 P < 0.01) or history of Bacille Calmette-Guérin (BCG) vaccination (RR undefined; P < 0.01). Risk was not associated with specific aircraft or seat relative to the index case for US-born contacts. All five TST converters were born in countries where BCG vaccine is routinely given.

CONCLUSION

The positive TST reactions and conversions suggest boosting from BCG vaccination or prior exposure in TB-endemic countries. Since two positive contacts had no other identified risk factor, TB transmission on board the aircraft could not be excluded. Contact investigation of exposed aircraft passengers should be considered on a case-by-case basis, with consideration of the infectiousness of the ill passenger and the flight circumstances.

Leptospira interrogans serovar grippotyphosa infection in dogs

Leptospirosis attributed to infection with serovar grippotyphosa was diagnosed in 11 dogs. In naturally and experimentally infected dogs, a stereotypic serologic response to infection with Leptospira serovar grippotyphosa was detected. Although the highest serum antibody titers developed against serovar grippotyphosa, most dogs also had lower titers against serovars bratislava and pomona. Acute renal failure was evident in 10 dogs. One dog died prior to initiation of treatment; the remaining 10 dogs were treated with antibiotics and fluids. Two dogs were euthanatized, 2 dogs recovered without clinical or biochemical evidence of residual renal dysfunction, and 6 dogs recovered but had varying degrees of renal insufficiency. Hepatic involvement appeared to be a minor component of the disease in these dogs. Our results indicate that Leptospira serovar grippotyphosa infection is an important problem in dogs and should be considered when evaluating a dog with renal failure.

Peripheral portal venous blood flow alterations induced by hepatic masses: evaluation with color and pulsed Doppler sonography

We examined 29 patients with intra- and extrahepatic masses and 10 normal volunteers with duplex and color Doppler ultrasonography. Portal blood flow adjacent to the masses was categorized as anterograde, retrograde, or nondetectable and was correlated with lesion size, character, and location. Anterograde flow was documented in the main portal vein and in the central right and left portal veins in all patients and volunteers. Flow in the peripheral portal veins near the lesion examined was retrograde in 17, anterograde in 10, and nondetectable in two of the patients. Retrograde peripheral flow was seen only in solid lesions, abscesses, and large subcapsular hematomas. Peripheral portal flow was anterograde in all of the volunteers. This study confirms that color Doppler sonography can detect alterations in portal flow induced by intra- and extrahepatic masses. The relatively common presence of peripheral portal flow reversal in patients with metastases and hepatocellular carcinomas indicates that it is not a reliable sign for differentiation between these entities.

Idiopathic anaphylaxis: a series of 335 cases

BACKGROUND

Idiopathic anaphylaxis is anaphylaxis with no definable etiology and no trigger by exogenous allergens. Initially described in 1978, idiopathic anaphylaxis has been subsequently characterized and treatment protocols have been established.

OBJECTIVE

The demographics and course of 335 patients (225 previously reported) treated with prednisone, hydroxyzine, and albuterol are now reported.

RESULTS

Ages ranged from 5 to 83 years. There were nine new pediatric patients in this series totaling 14 (4.2%). Atopy was common (48%) with 34 new patients with asthma. The duration of symptoms prior to presentation ranged from three days to 27 years. One hundred thirty-two patients with idiopathic anaphylaxis were available for follow-up. Twenty of these are currently receiving prednisone for control of idiopathic anaphylaxis, seven of them as part of their initial therapy, and ten for control of recurrence of symptoms. Three patients required continuous alternate day prednisone for control of symptoms (corticosteroid-dependent idiopathic anaphylaxis). Of the 335 patients, there were no longer any patients with the diagnosis of malignant idiopathic anaphylaxis defined as requiring prednisone, 20 mg daily, or 60 mg every other day, for control of idiopathic anaphylaxis. Of the six patients previously diagnosed with malignant idiopathic anaphylaxis, five no longer required prednisone and one has a decreased prednisone requirement of 20 mg on alternate days. Hospital visits were significantly reduced by the management regimens. There were no fatalities from idiopathic anaphylaxis in this series.

CONCLUSIONS

The incidence of idiopathic anaphylaxis is increasing in our practice with more patients being evaluated each year. During 1104 patient years of observation (the longest period of single patient observation being 24 years), no inciting agent has been found responsible for the anaphylactic symptoms. Prognosis continues to remain good with the majority of patients achieving remission with pharmacotherapy.

cDNA cloning and chromosome mapping of the human Fe65 gene: interaction of the conserved cytoplasmic domains of the human beta-amyloid precursor protein and its homologues with the mouse Fe65 protein

Using the yeast two hybrid system, a mouse embryo cDNA library was screened for proteins that interact with the C-terminus of the human beta-amyloid precursor protein (beta PP). A fusion protein was identified that interacts specifically with the cytoplasmic domain of beta PP and does not interact with the beta-amyloid region. The protein encoded by this partial mouse cDNA is identical to the C-terminus of the rat Fe65 protein. This mouse protein also interacts with the homologous C-terminal domains of the mouse amyloid precursor-like proteins, APLP1 and APLP2. These conserved cytoplasmic regions contain a common amino acid motif, Asn-Pro-Thr-Tyr, which has previously been shown to influence both the secretion and internalization of beta PP. Fe65 has been implicated in regulatory and cell signaling mechanisms because it contains two different motifs involved in protein binding, a WW domain (a variant of Src homology 3 domains) and a phosphotyrosine interaction domain (PID). Interestingly, the PID domain binds to the same motif present in the conserved cytoplasmic domains of the beta PP and beta PP-like proteins. RNA analyses reveal that Fe65 is predominantly expressed in brain and in the regions most affected by Alzheimer's disease (AD)-associated neuropathology. The human Fe65 mRNA was cloned from a fetal brain cDNA library. The message encodes a protein of 735 amino acids that is 95% identical to the rat Fe65 protein. The human Fe65 gene was mapped on human metaphase chromosomes to band 11p15 using fluorescence in situ hybridization.

The development of parenting: nursing resources

Successful parenting has a major impact on the emotional well-being and cognitive development of young children. Infants gain their sense of self at an early age through their interactions with their caregivers. Nurses can play a unique role in helping parents and caregivers learn about their infant's abilities and behavior and in providing interventions to foster positive parent-infant interactions. Several resources are presented that the professional can use to help parents learn about their newborn's individual communication patterns and needs.

Bladder washing cytology. Comparison of two analytic methods and two proposed quantitative criteria for carcinoma in situ

OBJECTIVE

To compare bladder washing cytology preparations created by the Nucleopore filter and slide centrifuge techniques and to evaluate a marker for carcinoma in situ (CIS).

STUDY DESIGN

Nucleopore filter and slide centrifuge preparations from 27 patients with urothelial carcinoma were compared and used to create two criteria for CIS. To study reproducibility, three observers evaluated 25 filter preparations for these CIS criteria.

RESULTS

The filter technique displayed more better-preserved single cancer cells (P = .02) and a higher percent group count (the number of cancer cell groups divided by the sum of the number of single cancer cells plus the number of cancer cell groups) (P = .005) than did the cytocentrifuge technique. The initial study showed that patients with many single tumor cells and lower percent group counts were more likely to have CIS than patients without this combined condition (P = .001). This CIS marker had moderate reproducibility (kappa = 0.47 +/- 0.12).

CONCLUSION

The filter technique had better cellular recovery and preservation of tumor cells than did the centrifuge technique. Quantitative cytologic criteria proposed in this study may be an indication that CIS may be present; improved sensitivity and specificity may be obtained if they are combined with other criteria.

Discrimination of methadone and cocaine by pigeons without explicit discrimination training

Pigeons were trained to peck a key on a variable-interval 2-min schedule of food reinforcement. Prior to each session, either 2.0 mg/kg methadone (n = 3), 3.0 mg/kg cocaine (n = 4), or 5.6 mg/kg cocaine (n = 2) was administered. When each pigeon's rate of pecking was stable, a range of doses of the training drug and saline were administered prior to 20-min extinction sessions separated by at least four training sessions. Rate of pecking during these extinction tests was generally an increasing function of dose, with the lowest rates obtained following saline and low doses and the highest rates obtained following doses near the training doses. Dose functions from pigeons trained with 5.6 mg/kg cocaine were steeper than those from pigeons trained with 3.0 mg/kg cocaine. Pigeons trained with methadone or 3.0 mg/kg cocaine were then given discrimination training, in which food reinforcement followed drug administration and 20-min extinction sessions followed saline administration. Rates of pecking under these conditions quickly diverged until near-zero rates were obtained following saline and high rates were obtained following drug. Discrimination training steepened dose functions for the training drugs, and the effects of several other substituted drugs depended on the pharmacology of the training drug. The pigeons trained with 5.6 mg/kg cocaine were tested with d-amphetamine, methadone, and morphine prior to discrimination training. d-Amphetamine increased rates dose dependently, and methadone and morphine did not. The results suggest that discriminative control by methadone and cocaine was established without explicit discrimination training.

Glucose load and renal sodium handling in mild essential hypertension on different sodium intakes

The aims of the present study were to investigate the effects of changes in sodium intake in patients with untreated mild essential hypertension on the hormonal (plasma renin activity and aldosterone) and renal tubular responses to short-term hyperinsulinemia as achieved by an oral glucose tolerance test (OGTT). Fourteen patients with essential hypertension (mean age, 46 years; average blood pressure (BP), 151/96 mm Hg) were studied. After a 1 week run-in period on their usual diet they entered a randomized double-blind crossover study of a week of low (10 mmol/day) vs a week of high (350 mmol/day) sodium intake. On the last day of each diet they underwent a standard 2-h OGTT. Blood and urines were taken hourly and segmental tubular sodium handling was assessed by the endogenous lithium clearance. The results demonstrate that the plasma insulin and glucose response to a short-term oral glucose load were not influenced significantly by the changes in dietary sodium intake. However, the glucose load was associated with marked renal sodium retention in the absence of any change in systemic BP. The reduction in renal sodium excretion was independent of circulating aldosterone but appeared to be due to an increase in renal distal tubular re-absorption.

Hydrolysis of cyclic guanosine monophosphate and cyclic adenosine monophosphate by the penis and aorta of the diabetic rat

OBJECTIVE

To investigate the hydrolysis of adenosine 3'5'-cyclic monophosphate (cAMP) and guanosine 3'5'-cyclic monophosphate (cGMP) by specific phosphodies-terases (PDEs) in the penis and aorta of diabetic rats.

MATERIALS AND METHODS

Non-ketonuric diabetes mellitus was induced in 10 Sprague-Dawley rats with streptozotocin. After 2 months, the rats were killed and their penises and aortae excised. The tissues were incubated with [3H]-cAMP and [3H]-cGMP and the degree of hydrolysis was assessed by separating [3H]-cAMP and [3H]-cGMP from [3H]-AMP and [3H]-GMP, respectively, in the incubation supernatants using thin layer chromatography (polyethyleneimine cellulose developed in 50 mmol/L KCl).

RESULTS

The hydrolysis of cAMP and cGMP was significantly reduced in penile and aortic tissue from diabetic rats compared to that of seven age-matched controls.

CONCLUSIONS

Such a reduction of PDE activity would result in increased intracellular cyclic nucleotide levels (and thus corporeal smooth muscle relaxation and erection). Consequently, the altered activity of PDE enzyme systems is not related aetiologically to the pathogenesis of diabetic erectile dysfunction. Furthermore, these data consolidate the concept that enhanced cyclic nucleotide synthesis and decreased degradation constitute an adaptive response to counteract the deleterious effects of diabetes mellitus on erectogenic mechanisms. The pathophysiology and therapeutic implications of these findings warrant further investigation.