What is the impact of one's chronic illness on his or her spouse's future chronic illness: a community-based prospective cohort study

BACKGROUND

Integrating a joint approach to chronic disease management within the context of a couple has immense potential as a valuable strategy for both prevention and treatment. Although spousal concordance has been reported in specific chronic illnesses, the impact they cumulatively exert on a spouse in a longitudinal setting has not been investigated. We aimed to determine whether one's cumulative illness burden has a longitudinal impact on that of their spouse.

METHODS

Data was acquired from a community-based prospective cohort that included Koreans aged 60 years and over, randomly sampled from 13 districts nationwide. Data from the baseline assessment (conducted from November 2010 to October 2012) up to the 8-year follow-up assessment was analyzed from October 2021 to November 2022. At the last assessment, partners of the index participants were invited, and we included 814 couples in the analysis after excluding 51 with incomplete variables. Chronic illness burden of the participants was measured by the Cumulative Illness Rating Scale (CIRS). Multivariable linear regression and causal mediation analysis were used to examine the longitudinal effects of index chronic illness burden at baseline and its change during follow-up on future index and spouse CIRS scores.

RESULTS

Index participants were divided based on baseline CIRS scores (CIRS < 6 points, n = 555, mean [SD] age 66.3 [4.79] years, 43% women; CIRS ≥ 6 points, n = 259, mean [SD] age 67.7 [4.76] years, 36% women). The baseline index CIRS scores and change in index CIRS scores during follow-up were associated with the spouse CIRS scores (β = 0.154 [SE: 0.039], p < 0.001 for baseline index CIRS; β = 0.126 [SE: 0.041], p = 0.002 for change in index CIRS) at the 8-year follow-up assessment. Subgroup analysis found similar results only in the high CIRS group. The baseline index CIRS scores and change in index CIRS scores during follow-up had both direct and indirect effects on the spouse CIRS scores at the 8-year follow-up assessment.

CONCLUSIONS

The severity and course of one's chronic illnesses had a significant effect on their spouse's future chronic illness particularly when it was severe. Management strategies for chronic diseases that are centered on couples may be more effective.

Shared Risk Factors for Depressive Disorder Among Older Adult Couples in Korea

Importance

Although couples may share many risk factors for depressive disorders in their lifetime, whether these factors mediate the shared risk of depressive disorders has rarely been investigated.

Objectives

To identify the shared risk factors for depressive disorder in couples and investigate their mediating roles in the shared risk of depressive disorders among older adult couples.

Design, Setting, and Participants

This nationwide, multicenter, community-based cohort study assessed 956 older adults from the Korean Longitudinal Study on Cognitive Aging and Dementia (KLOSCAD) and a cohort of their spouses (KLOSCAD-S) between January 1, 2019, to February 28, 2021.

Exposures

Depressive disorders of the KLOSCAD participants.

Main Outcomes and Measures

The mediating roles of shared factors in couples on the association between one spouse's depressive disorder and the other's risk of depressive disorders was examined using structural equation modeling.

Results

A total of 956 KLOSCAD participants (385 women [40.3%] and 571 men [59.7%]; mean [SD] age, 75.1 [5.0] years) and their spouses (571 women [59.7%] and 385 men [40.3%]; mean [SD] age, 73.9 [6.1] years) were included. The depressive disorders of the KLOSCAD participants were associated with an almost 4-fold higher risk of depressive disorders in their spouses in the KLOSCAD-S cohort (odds ratio, 3.89; 95% CI, 2.06-7.19; P < .001). Social-emotional support mediated the association between depressive disorders in the KLOSCAD participants and their spouses' risk of depressive disorders by itself (β = 0.012; 95% CI, 0.001-0.024; P = .04; mediation proportion [MP] = 6.1%) and through chronic illness burden (β = 0.003; 95% CI, 0.000-0.006; P = .04; MP = 1.5%). Chronic medical illness burden (β = 0.025; 95% CI, 0.001-0.050; P = .04; MP = 12.6%) and presence of a cognitive disorder (β = 0.027; 95% CI, 0.003-0.051; P = .03; MP = 13.6%) mediated the association.

Conclusions and Relevance

The risk factors shared by older adult couples may mediate approximately one-third of the spousal risk of depressive disorders. Identification of and intervention in the shared risk factors of depression among older adult couples may reduce the risk of depressive disorders in the spouses of older adults with depression.

Deep learning-based diagnosis of Alzheimer's disease using brain magnetic resonance images: an empirical study

The limited accessibility of medical specialists for Alzheimer's disease (AD) can make obtaining an accurate diagnosis in a timely manner challenging and may influence prognosis. We investigated whether VUNO Med-DeepBrain AD (DBAD) using a deep learning algorithm can be employed as a decision support service for the diagnosis of AD. This study included 98 elderly participants aged 60 years or older who visited the Seoul Asan Medical Center and the Korea Veterans Health Service. We administered a standard diagnostic assessment for diagnosing AD. DBAD and three panels of medical experts (ME) diagnosed participants with normal cognition (NC) or AD using T1-weighted magnetic resonance imaging. The accuracy (87.1% for DBAD and 84.3% for ME), sensitivity (93.3% for DBAD and 80.0% for ME), and specificity (85.5% for DBAD and 85.5% for ME) of both DBAD and ME for diagnosing AD were comparable; however, DBAD showed a higher trend in every analysis than ME diagnosis. DBAD may support the clinical decisions of physicians who are not specialized in AD; this may enhance the accessibility of AD diagnosis and treatment.

Mood disorders increase mortality mainly through dementia: A community-based prospective cohort study

OBJECTIVE

The effects of mood disorders on mortality may be mediated by their effects on the risk of dementia, and interventions to reduce the occurrence of dementia may reduce their overall mortality. This study aimed to investigate the direct effects of depressive and bipolar disorders on the 6-year risk of mortality and also their indirect effects on mortality due to their effect on the risk of dementia.

METHODS

A total of 5101 Koreans were selected from a community-based prospective cohort study, and 6-year risks of mortality and dementia in participants with depressive and bipolar disorders were estimated by Cox proportional hazard analysis. The direct and indirect effects of depressive and bipolar disorders on the risk of mortality were estimated using structural equation modeling.

RESULTS

The depressive and bipolar disorder groups showed 51% and 85% higher 6-year mortality, and 82% and 127% higher risk of dementia, respectively, compared to euthymic controls. The effects of depressive and bipolar disorders on mortality were mainly mediated by their effects on the risk of dementia in a structural equation model. The direct effects of each mood disorder on mortality were not significant.

CONCLUSION

Both depressive and bipolar disorders increased the risks of mortality and dementia, and the effects of mood disorders on mortality were mainly mediated through dementia. As dementia occurs later in life than mood disorders, measures to prevent it may effectively reduce mortality in individuals with a history of mood disorders, as well as being more feasible than attempting to control other causes of death.

Exploration of Cognitive Outcomes and Risk Factors for Cognitive Decline Shared by Couples

Importance

Although couples could share many risk factors of cognitive disorders in their lifetime, whether shared risk factors mediate the shared risk of cognitive disorders has rarely been investigated.

Objective

To identify the risk factors of cognitive decline shared within couples and investigate their mediating roles in the shared risk of cognitive disorders and cognitive functions within couples.

Design, Setting, and Participants

A prospective cohort study was launched in November 1, 2010, and 784 participants were followed up every 2 years until December 31, 2020. This nationwide, multicenter, community-based study included older couples from the Korean Longitudinal Study on Cognitive Aging and Dementia (KLOSCAD) and a cohort of their spouses (KLOSCAD-S).

Exposures

The cognitive disorder of a spouse was defined as mild cognitive impairment or dementia.

Main Outcomes and Measures

The mediating roles of factors shared within couples on the association between one spouse's cognitive disorder and the other's risk of cognitive disorders was examined with structural equation modeling.

Results

Included were 784 KLOSCAD participants (307 women [39.2%] and 477 men [60.8%]; mean [SD] age, 74.8 [4.8] years) and their spouses (477 women [60.8%] and 307 men [39.2%]; mean [SD] age, 73.6 [6.2] years). The cognitive disorder of the KLOSCAD participants was associated with almost double the risk of cognitive disorder of their spouses in the KLOSCAD-S cohort (odds ratio, 1.74; 95% CI, 1.12-2.69; P = .01). History of head injury (β = 0.50; 95% CI, 0.09-0.90; P = .02) and age (β = 2.57; 95% CI, 1.37-3.76; P < .001) mediated the association between cognitive disorder in the KLOSCAD participants and their spouses' risk of cognitive disorder. Physical inactivity mediated the association through major depressive disorder (β = 0.33, 95% CI, 0.09-0.57, P = .006 for physical inactivity; β = 0.28, 95% CI, 0.13-0.44, P < .001 for major depressive disorder). These factors similarly mediated the association between spousal cognitive disorder and cognitive functions such as memory and executive function.

Conclusions and Relevance

These findings suggest that the risk factors shared within couples may mediate approximately three-quarters of the spousal risk of cognitive disorders. Identification of and intervention in the shared risk factors of dementia within couples may reduce the risk of cognitive disorders in the spouses of people with dementia.

Influence of Plasma Fibronectin on the Response to Infusion of Thrombin and Adenosine Diphosphate

An important physiological anti-thrombotic function has been suggested for plasma fibronectin and the reticuloendothelial system. The current study evaluated the effects of specific immunological fibronectin depletion and fibronectin supplementation upon resistance to infusion of thrombin and ADP in terms of mortality, mean arterial blood pressure and circulating levels of platelets, fibrinogen and fibrin degradation products. Mortality data indicated that rats with reduced fibronectin levels had reduced resistance to thrombin or adenosine diphosphate infusion. The increased lethality was characterized by reduced circulating levels of fibrinogen and platelets while fibrin degradation product levels rose. The infusion of ADP or thrombin in fibronectin supplemented rats failed to elicit higher mortality or reduce fibrinogen or platelet levels further. These data are consistent with the hypothesis that resistance to excessive coagulation and/or platelet aggregation is correlated to circulating plasma fibronectin levels. It is suggested that by direct effects and/ or acting as an opsonin for RES phagocytosis, plasma fibronectin acts as an important anti-thrombotic mechanism.

Effect of levitra on sustenance of erection (EROS): an open-label, prospective, multicenter, single-arm study to investigate erection duration measured by stopwatch with flexible dose vardenafil administered for 8 weeks in subjects with erectile dysfunction

To investigate the change of erection duration measured by stopwatch with flexible dose vardenafil administered for 8 weeks in subjects with erectile dysfunction (ED). Effect of levitra on sustenance of erection was an open-label, prospective, multicenter and single-arm study designed to measure the duration of erection in men with ED receiving a flexible dose of vardenafil over an 8-week treatment period. Patients were instructed to take vardenafil 10 mg 60 min before attempting the intercourse. Vardenfil could be increased to 20 mg or decreased to 5 mg concerning patients' efficacy and safety. Following the initial screening, patients entered a 4-week treatment-free run-in phase and 8-week treatment period, during which they were instructed to attempt intercourse at least four times on four separate days. A total of 95 men were enrolled in 10 centers. After the 8 weeks treatment, the mean duration of erection leading to successful intercourse was statistically superior when patients were treated with vardenafil. After an 8-week treatment, the duration of erection leading to successful intercourse was 9.39 min. There were significant benefits with vardenafil in all domains of International Index of Erectile Function. Secondary efficacy end points included success rate of penetration, maintaining erection, ejaculation and satisfaction were superior when patients were treated with vardenafil. There was a significant correlation between duration of erection with other sexual factors. Also partner's sexual satisfaction was increased with vardenafil. Most adverse events were mild or moderate in severity. Vardenafil was safe and well tolerated. Vardenafil therapy provided a statistically superior duration of erection leading to successful intercourse in men with ED with female partner.

The effects of intravesical chemoimmunotherapy with gemcitabine and Bacillus Calmette-Guérin in superficial bladder cancer: a preliminary study

This prospective study investigated the long-term effects of intravesical chemoimmunotherapy with gemcitabine (GEM) and bacillus Calmette-Guérin (BCG; n = 36) versus BCG alone (n = 51) for the treatment of superficial bladder cancer. For the chemoimmunotherapy (GEM + BCG) group, GEM (1000 mg) was instilled immediately after transurethral resection of bladder tumour (TURBT) and again (2000 mg) 1 week later. From 2 to 7 weeks after TURBT, BCG was instilled into the bladder of all patients once weekly. The recurrence-free period of the GEM + BCG group (24.13 months) was significantly longer than that of the BCG monotherapy group (19.81 months). The overall recurrence rate was similar between the groups, although at 6 and 9 months post-TURBT, GEM + BCG produced a significantly lower rate of recurrence compared with BCG alone. This study suggests that intravesical chemoimmunotherapy with GEM + BCG is effective in reducing early tumour recurrence and in prolonging the recurrence-free period of superficial bladder cancer.

The Effects of Long-Term Administration of Oral Desmopressin on the Baseline Secretion of Antidiuretic Hormone and Serum Sodium Concentration for the Treatment of Nocturia: A Circadian Study

PURPOSE

We assessed the effects of long-term oral desmopressin on serum sodium and baseline antidiuretic hormone secretion in elderly patients with nocturia.

MATERIALS AND METHODS

A total of 15 elderly male patients with severe nocturia (greater than 3 voids nightly) who did not show hyponatremia within 7 days of administration of 0.2 mg desmopressin were enrolled in this study. Desmopressin (0.2 mg) was administered orally nightly for 1 year. Before and 1 month after the 1-year medication 24-hour circadian studies were performed to monitor changes in antidiuretic hormone. Every 3 months during the 1-year medication serum changes and timed urine chemistry were monitored.

RESULTS

Desmopressin significantly decreased nocturnal urine output and the number of nocturia episodes (p<0.01). Compared to before treatment desmopressin gradually decreased serum sodium and induced statistically but not clinically significant hyponatremia after 6 months of treatment. After discontinuing desmopressin serum sodium returned to the normal range in all patients. There were no significant differences when baseline and posttreatment endogenous antidiuretic hormone were compared. No serious systemic complications were found during medication.

CONCLUSIONS

Long-term desmopressin administration gradually decreased the serum concentration and induced significant hyponatremia from 6 months in patients who did not show initial hyponatremia. Long-term administration of desmopressin for 1 year in elderly patients did not affect baseline antidiuretic hormone secretion. For long-term desmopressin administration serum sodium should be assessed regularly, at least every 6 months.

Effects of glans penis augmentation using hyaluronic acid gel for premature ejaculation

The main limitation of medical treatment for premature ejaculation is recurrence after withdrawal of medication. We evaluated the effect of glans penis augmentation using injectable hyaluronic acid (HA) gel for the treatment of premature ejaculation via blocking accessibility of tactile stimuli to nerve receptors. In 139 patients of premature ejaculation, dorsal neurectomy (Group I, n=25), dorsal neurectomy with glandular augmentation (Group II, n=49) and glandular augmentation (Group III, n=65) were carried out, respectively. Two branches of dorsal nerve preserving that of midline were cut at 2 cm proximal to coronal sulcus. For glandular augmentation, 2 cc of HA was injected into the glans penis, subcutaneously. At 6 months after each procedure, changes of glandular circumference were measured by tapeline in Groups II and III. In each groups, ejaculation time, patient's satisfaction and partner's satisfaction were also assessed. There was no significant difference in preoperative ejaculation time among three groups. Preoperative ejaculation times were 89.2+/-40.29, 101.54+/-59.42 and 96.5+/-52.32 s in Groups I, II and III, respectively. Postoperative ejaculation times were significantly increased to 235.6+/-58.6, 324.24+/-107.58 and 281.9+/-93.2 s in Groups I, II and III, respectively (P<0.01). The percentage of postoperative satisfaction in both patient and his partner was 68% (17/25) and 44% (7/16) in Group I, 80% (39/49) and 66% (25/38) in Group II and 75% (49/65) and 62% (32/52) in Group III, respectively. Maximal glandular girth was significantly increased from 9.16+/-0.59 to 10.95+/-0.4 cm in Group II and 8.95+/-0.54 to 11.67+/-0.71 cm in Group III, respectively. These results suggest that glandular augmentation with injectable HA gel is a safe and effective modality to reduce sensory of glans penis. Long-term follow-up for residual volume and efficacy should be requested to establish its precise therapeutic potentials in premature ejaculation.

Human glans penis augmentation using injectable hyaluronic acid gel

Although augmentation phalloplasty is not an established procedure, some patients still need enlargement of their penis. Current penile augmentation is girth enhancement of penile body by dermofat graft. We performed this study to identify the efficacy and the patient's satisfaction of human glans penis augmentation with injectable hyaluronic acid gel. In 100 patients of subjective small penis (Group I) and 87 patients of small glans after dermofat graft (Group II), 2 cm(3) of hyaluronic acid gel was injected into the glans penis, subcutaneously. At 1 y after injection, changes of glandular diameter were measured by tapeline. Patient's visual estimation of glandular size (Gr 0-4) and patient's satisfaction (Grade (Gr) 0-4) were evaluated, respectively. Any adverse reactions were also evaluated. The mean age of patients was 42.2 (30-70) y in Group I and 42.13 (28-61) y in Group II. The maximal glandular circumference was significantly increased compared to basal circumference of 9.13+/-0.64 cm in Group I (P<0.01) and 9.49+/-1.05 cm in Group II (P<0.01) at 1 y after injection. Net increase of maximal glandular circumference after glans augmentation was 14.93+/-0.80 mm in Group I and 14.78+/-0.89 mm in Group II. In patient's visual estimation, more than 50% of injected volume was maintained in 95% of Group 1 and 100% of Group II. The percentage of postoperative satisfaction (Gr 4, 5) was 77% in Group 1 and 69% in Group II. There was no abnormal reaction in area feeling, texture, and color. In most cases, initial discoloration by glandular swelling recovered to normal within 2 weeks. There were no signs of inflammation and no serious adverse reactions in all cases. These results suggest that injectable hyaluronic acid gel is a safe and effective material for augmentation of glans penis.

Effect of TCDD on corpus cavernosum histology and smooth muscle physiology

A polyhalogenated aromatic hydrocarbon, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), is one of the most potent toxic environmental pollutants. Decreases in spermatogenesis and the ability to conceive and carry a pregnancy to term are the most sensitive signs of reproductive toxicity by TCDD in the mammal, but no report of its effect on the erectile function exists. We performed this study to investigate the effect of TCDD on the erectile function. New Zealand white rabbits were treated intraperitoneally with 1 microg/kg of TCDD. At 4 (Gr I) and 8 (Gr II) weeks after the administration of TCDD, cavernosal tissues were harvested for strip study in the organ bath and testes were prepared for histologic examination. Compared to the maximal amplitude of 17.1+/-4.12 mN in normal control (Gr III), the contractions to cumulative concentrations of NE (10(-8)-10(-4) M) were significantly decreased to 6.57+/-1.34 and 5.45+/-1.01 mN in Groups I and II, respectively. Compared to 51.12+/-7.38% in Gr III, relaxation to cumulative concentration (10(-8)-10(-4) M) of acetylcholine was significantly decreased to 17.25+/-2.17% (Gr I) and 9.73+/-2.17% (Gr II) at a concentration of 10(-4) M, respectively. Compared to 75.12+/-13.18% in Gr III, relaxation to cumulative concentration (10(-8)-10(-4) M) of SNP was significantly decreased to 31.49+/-7.89% (Gr I) and 18.54+/-6.12% (Gr II) at a concentration of 10(-4) M, respectively. Histologically, intracavernosal fibrosis, abnormal subtunical deposition of fat and decreased sinusoidal space with consequent increase of trabecular smooth muscle contents were identified in TCDD-treated groups. In TCDD-treated animals, seminiferous tubules showed a decrease of germ cells with vacuolar degeneration and apoptotic cells. Spermatids were hardly seen. These results suggest that TCDD inhibits spermatogenesis and has a potential harmful effect on erectile function via changes of corpus cavernosum histology and smooth muscle physiology.

Augmentation of glans penis using injectable hyaluronic acid gel

Recently, injectable hyaluronic acid gel has been widely used in soft-tissue augmentation. We performed this study to identify the feasibility of hyaluronic acid gel for the augmentation of the glans penis. In experiment I, 0.2 cm(3) of hyaluronic acid gel (HA) was injected into the dermis of the glans penis of 25 New Zealand white rabbits via a 30 G needle. At 3, 7, 14, 30, and 90 days after injection, histological changes of glans were studied, respectively. In experiment II, 0.5 cm(3) of HA was injected into the dermis of the glans penis of 14 Beagle dogs via a 27 G needle. At 6 months after injection, histological changes of the glans penis were also evaluated. At the time of autopsy, the lung, liver, and spleen were studied for systemic adverse reaction in each separate experiment. In experiment I, various sized cavities filled with amorphous basophilic materials were noted in the lamina propria and corpus spongiosum of the glans penis. All implants were positively stained on alcian blue. The intensity decreased in a time-dependent manner. Until 14 days, minimal inflammatory reactions were noted, but no signs of inflammation were identified at 90 days. With the gradual decrease of inflammation, fibrosis and deposition of collagen were noted. In experiment II, implants were well maintained at 6 months after injection in the lamina propria. Grade 1 of the inflammatory reaction was noted in one case. In both the experiments, all the specimens were free from any foreign body reaction and systemic adverse reactions. In conclusion, these results suggest that hyaluronic acid gel can be easily injected into the lamina propria of the glans penis and reside until 6 months. Injectable hyaluronic acid gel has a potential as a new bioimplant for the augmentation of the glans penis.

In vivo characterization of a prostate-specific antigen promoter-based suicide gene therapy for the treatment of benign prostatic hyperplasia

To develop a novel gene therapeutic modality for the effective treatment of benign prostatic hyperplasia (BPH), we investigated the properties of toxic gene therapy utilizing prostate-specific antigen (PSA) promoter driving herpes simplex virus thymidine kinase (HSV-TK) suicide gene to induce highly selective molecular ablation of epithelial cells with minimal systemic toxicity in canine prostate. Replication-defective recombinant adenoviral vectors containing HSV-TK gene under transcriptional control of long PSA promoter (Ad-PSA-HSV-TK) were developed and delivered in an situ manner. Briefly, laparotomies were performed and Ad-PSA-HSV-TK (1 x 10(9) PFUs) was injected into the left lateral lobe of prostate only on days 1 and 7 with appropriate prodrug acyclovir in adult Beagle dogs. The therapeutic efficacy was evaluated on the 56th experimental day. The striking apoptosis of epithelial cells was identified in the treated left half of canine prostate on TUNEL assay. On immunohistochemical studies, there was markedly decreased number of PSA-secreting epithelial cells compared to control. Also significant atrophy of prostate glands, associated with dense infiltration of lymphocytes and plasma cells, was identified in the treated side. The PSA promoter-based suicide gene therapy induced highly selective and definite ablation of epithelial cells in benign canine prostate. Our novel approach could open opportunity of gene therapeutic modality for the treatment of clinical BPH.

A double-blind, randomised- placebo, controlled, parallel group, multicentre, flexible-dose escalation study to assess the efficacy and safety of sildenafil administered as required to male outpatients with erectile dysfunction in Korea

The efficacy and safety of sildenafil was evaluated in a randomiSed, double-blind, placebo-controlled, flexible-dose study in Korean men aged 28-78 y with erectile dysfunction (ED) of broad-spectrum aetiology and more than 6 months duration. A total of 133 patients were randomised at six centres in Korea to receive either sildenafil (50 mg initially, increased if necessary to l00 mg or decreased to 25 mg depending on efficacy and tolerance) (n=66) or matching placebo (n=67) taken on an 'as needed' basis l h prior to anticipated sexual activity for a period of 8 weeks. At the end of this time, the primary efficacy variables relating to the achievement and maintenance of erections sufficient for sexual intercourse, and the secondary efficacy variables, which included: (1) the five separate domains of sexual functioning of the International Index of Erectile Function (IIEF) scale, (2) the percentage of successful intercourse attempts, and (3) a global assessment of erections, were all statistically significantly improved by sildenafil in comparison with placebo (P&<0.0001). Treatment-related adverse events occurred in 56.1% of patients receiving sildenafil and 20.9% receiving placebo. The most common adverse events with sildenafil were vasodilatation (flushing), headache and abnormalities in colour vision (31.8, 22.7 and 6.1% of patients, respectively), and most were mild in nature. The efficacy and safety of sildenafil in this population of Korean men appears similar to that reported in other studies in western populations.

Allium sativum potentiates suicide gene therapy for murine transitional cell carcinoma

This study evaluated the synergistic effect of Allium sativum (AS) with suicide gene therapy for transitional cell carcinoma (TCC) of the bladder. Subcutaneous TCCs were established in syngeneic C3H/He mice with 1 x 10(5) MBT-2 cells. AS liquid extract was injected at the site of tumor transplantation on Day 1 for three weeks (Experiment I) and into the established tumors weekly for five weeks (Experiment II) in combination with or without gene therapy using a replication-defective adenoviral vector containing a herpes simplex virus thymidine kinase (HSV-TK) gene under the transcriptional control of Rous sarcoma virus (RSV) promoter (Ad-RSV-TK, 5 x 10(8) plaque-forming units) plus ganciclovir (20 mg/kg/day i.p.). AS demonstrated a statistically significant reduction in incidence of TCC (cumulative dose 25 mg of AS). Combination AS-suicide gene therapy significantly inhibited the tumor growth compared with the controls, which was evidenced by apoptosis on histomorphological and immunohistochemical studies. These results suggest that AS had a definite antitumor effect in inhibiting tumorigenesis and growth of TCC in a murine model. AS treatment combined with suicide gene therapy had significant additive antitumor effects on TCC and may provide a novel and effective treatment modality for TCC of the bladder.

Statin drugs and dietary isoprenoids downregulate protein prenylation in signal transduction and are antithrombotic and prothrombolytic agents

Statins and various isoprenoids of dietary origins inhibit L-mevalonic acid synthesis, which in turn downregulates cholesterol and various other dependent substances, including farnesyl- and geranylgeranyl-conjugated proteins involved in cell signaling processes. Such signaling processes are stimulated by protease-activated receptor-1 (PAR-1), which upon activation, causes the expression of various substances including tissue factor (TF) and plasminogen activator inhibitor-1 (PAI-1). Tissue factor promotes thrombin generation, where thrombin stimulates a variety of cellular processes, as well as activating PAR-1 to produce more thrombin. Statins downregulate TF mitigating thrombin generation and also downregulate PAI-1, which normally consumes tissue plasminogen activator (tPA). In the absence of PAI-1, tPA activates plasminogen to generate plasmin. Thus, statins behave as antithrombotic agents and prothrombolytic agents.

The effects of a selective noradrenaline reuptake inhibitor on the urethra: an in vitro and in vivo study

OBJECTIVE

To identify the effects of a selective noradrenaline reuptake inhibitor (venlafaxine) on urethral perfusion pressure (UPP) in rabbits and rats, and thus assess its therapeutic potential for treating stress urinary incontinence.

MATERIALS AND METHODS

Strips of bladder and proximal urethra were prepared from female New Zealand White rabbits. Each strip was electrically stimulated and the contractile responses of controls strips compared with those after pretreatment with venlafaxine (100 micromol/L). In separate experiments using 80 adult female Sprague-Dawley rats (250-300 g), changes in intravesical pressure and UPP after the intra-arterial and intra-urethral administration of phenylephrine, phentolamine, fluoxetine and venlafaxine were monitored using double-lumen catheters.

RESULTS

Pretreatment with venlafaxine significantly decreased the contraction of bladder strips (P=0.01) and significantly increased the contraction of urethral strips (P=0.008). In vivo, phenylephrine administered by both routes significantly increased UPP (P=0.02); phentolamine (arterial) significantly decreased UPP (P=0.001); fluoxetine (arterial) had no effect on UPP, and venlafaxine (both routes) significantly increased UPP (both P<0.001). The intravesical pressure was not changed significantly in any animal.

CONCLUSIONS

Venlafaxine effectively increased UPP both in vitro and in vivo; these results imply that venlafaxine may be useful for treating stress urinary incontinence, by increasing the UPP.

Bisphenol A inhibits penile erection via alteration of histology in the rabbit

Despite extensive research into the toxicity of bisphenol A (BPA), no report of its effect on erectile function exists. We performed this study to investigate the effect of BPA on erectile function. New Zealand white rabbits were treated intraperitoneally with 150 mg/kg of BPA every other day for 12 days (cumulative dose of 900 mg/kg). Four and 8 weeks after administration of BPA, the contractions and relaxation of cavernosal tissue strips were significantly suppressed in the BPA-treated animals compared to the control animals. Histologically, thickening of tunica albuginea, subtunical deposition of fat and decreased sinusoidal space with consequent increase of trabecular smooth muscle content were observed in the BPA-treated animals. These results suggest that xenoestrogen BPA may affect the erectile function through evident histological changes of the penis.

The influence of prostate volume on the prostate-specific antigen (PSA) level adjusted for the transition zone volume and free-to-total PSA ratio: a prospective study

OBJECTIVES

To evaluate the influence of prostate volume on the prostate-specific antigen (PSA) level adjusted for the transition zone volume (PSAT) and free-to-total PSA ratio (f/tPSA) in detecting prostate cancer in men with intermediate PSA levels of 4.1-10.0 ng/mL.

PATIENTS AND METHODS

From March 1997 to June 1999, the f/tPSA and PSAT were measured in 105 patients who underwent ultrasound-guided systemic biopsies and had a PSA level of 4.1-10.0 ng/mL, with an apparently normal prostate on a digital rectal examination. The PSAT and f/tPSA were evaluated in all patients and in subgroups of patients with small (< 40 mL) or large (> or = 40 mL) prostates, using receiver operating characteristic (ROC) curves.

RESULTS

Total prostate volume was highly correlated with transition zone volume in all patients and in both subgroups (P < 0.001). In all 105 patients, PSAT had a sensitivity of 82% and its use would have avoided the largest number of unnecessary biopsies (87% specificity) at a threshold value of 0.35 ng. In men with small prostates f/tPSA and PSAT had a high sensitivity and specificity, at threshold values of 0.12 and 0.35 ng, respectively. In large prostates the PSAT was superior to f/tPSA in detecting prostate cancer.

CONCLUSIONS

These results suggest that both f/tPSA and PSAT are useful in detecting prostate cancer in men with small prostates, while PSAT is superior to f/tPSA in detecting prostate cancer in men with large prostates.

Adenovirus-mediated suicide-gene therapy using the herpes simplex virus thymidine kinase gene in cell and animal models of human prostate cancer: changes in tumour cell proliferative activity

OBJECTIVES

To determine the feasibility and efficacy of suicide-gene therapy using adenovirus (Ad)-mediated herpes simplex virus thymidine kinase (HSV-TK) and the prodrug acyclovir, and to evaluate changes in the biological phenotype for tumour cell proliferative activity after suicide-gene therapy in animal models of human prostate cancer.

MATERIALS AND METHODS

Using a replication-defective adenoviral vector (cytomegalovirus, CMV) containing the beta-galactosidase gene (Ad-CMV-beta-gal) as a control and Ad-CMV-TK as the therapeutic vector under the transcriptional control of the CMV promoter, transduction efficiency was assessed in vitro by infecting LNCaP and PC-3 androgen-dependent and independent human prostate cancer cells with Ad-CMV-beta-gal, and using X-gal staining. The TK activity in prostate cancer cells infected with Ad-CMV-TK was determined by measuring TK-mediated [3H]-gancyclovir phosphorylation. The sensitivity of LNCaP and PC-3 cells to Ad-CMV-TK in vitro was determined after infection with the therapeutic vector with or without acyclovir. The inhibition of PC-3 tumour growth in vivo induced by the Ad-CMV-TK/acyclovir suicide-gene system was assessed in separate and controlled experiments using human prostate cancer mouse models. Ki-67 proliferative antigen and proliferating cell nuclear antigen (PCNA), both useful proliferative indices, were evaluated using immunohistochemical staining (MIB-1 monoclonal antibody and monoclonal anti-PCNA antibody) in formalin-fixed, paraffin-embedded tissues from gene therapy-treated and control animals.

RESULTS

The mean TK activity was significantly higher in LNCaP and PC-3 cells infected with Ad-CMV-TK than in cells infected with Ad-CMV-beta-gal, used as a control (P < 0.05). The growth of human prostate cancer cells with Ad-CMV-TK was significantly inhibited by adding acyclovir in vitro (P < 0.05). In the in vivo experiments using the PC-3 human prostate cancer mouse model, tumour volume and growth was lower in mice treated with Ad-CMV-TK/acyclovir than in those treated with Ad-CMV-TK only, acyclovir only or untreated (controls) (P < 0.05). Histochemical staining of tumour tissues showed that Ad-CMV-TK/acyclovir destroyed PC-3 tumours through tumour cell death and apoptosis, with local lymphatic infiltration. The mean PCNA labelling index in prostate cancer cells of mice treated with Ad-CMV-TK/acyclovir was significantly lower than that in untreated controls (P < 0.05, Mann-Whitney U-test). The Ki-67 labelling index in prostate cancer cells of mice treated with Ad-CMV-TK/acyclovir was also lower than that in untreated controls (P < 0.05, Student's t-test). Adenovirus-mediated suicide-gene therapy using the HSV-TK gene decreased the proliferative activity of PC-3 human prostatic cancer cells in vivo.

CONCLUSIONS

Adenovirus-mediated suicide-gene therapy using an HSV-TK/acyclovir system provided effective therapy in an experimental human prostate cancer mouse model, by significantly inhibiting tumour growth and decreasing the proliferative activity of human prostate cancer cells. Such therapy could be developed as a novel method for treating patients with androgen-independent prostate cancer.

Family risk and resiliency factors, substance use, and the drug resistance process in adolescence

Recent approaches to drug prevention have emphasized risk and resiliency factors. Two models have been developed to explain these factors, one which posits that separate elements make up each set and the other which posits that a single factor can be either a risk or a resiliency factor depending on, for example, if it is present (resiliency) or absent (risk). This study tested these models and attempted to compare the effects of risk and resiliency across gender and ethnicity. Results support the model in which risk and resiliency are discrete sets of factors and demonstrate that overall resiliency factors play a larger role than risk factors in substance use and drug resistance processes. However, gender proved to be an important moderator of these effects. For adolescent males, resiliency has an indirect effect on overall substance use through age of first use, while risk has a direct effect on overall substance use. For adolescent females, resiliency has a direct effect on overall substance use and risk has an indirect effect through age of first use. This indicates that while early interventions are important for both genders, resiliency factors must be dealt with before initiation of substance use for males. Findings did not differ substantially across ethnicity, although the small African-American sample size may have limited power to detect differences.

Altered contractile response of penis under hypoxia with metabolic acidosis

Previous studies concerning ischemic priapism revealed that hypoxia alters the erectile and contractile responses of penis. But the effects of accompanying acidosis on those responses have not been fully evaluated or understood yet. We performed this study to elucidate the role of acidosis on the trabecular smooth muscle contractility like in ischemic priapism. Under the general anesthesia, 55 mature male cats were conditioned to systemic metabolic acidosis by hypoventilation by animal ventilator. The changes of intracavernous pressure (ICP) to erectogenic agents (acetylcholine, L-arginine, prostaglandin E1: PGE1), erectolytic agents (epinephrine, thromboxane A2; TXA2), K channel-related drugs (pinacidil, 4-aminopyridine, tetraethylammonium; TEA, glibenclamide) and calcium ionophore were monitored at Set 1 (PO2 > 60 mmHg, pH > 7.25), Set 2 (PO2 < 30 mmHg, 7.25 > pH > 7.0), Set 3 (PO2 < 30 mmHg, pH < 7.0), and Set 4 (PO2 > 60 mmHg, pH < 7.0) in vivo. At Set 1 and Set 2, epinephrine, TXA2, and ionomycin decreased the ICP by acetylcholine or PGE1 (n = 9, P < 0.01). The decrease of ICP was in order of epinephrine, TXA2 and ionomycin. Acidosis reduced the increase of ICP to acetylcholine or PGE1 (n = 8, P < 0.01), TXA2 or ionomycin did not affect ICP under severe acidosis but epinephrine decreased ICP even under severe acidosis (n = 7, P < 0.05). Pretreatment of potassium channel blockers did not suppress the increase of ICP by erectogenic agents under acidosis (n = 6, P < 0.05). Pinacidil did not affect ICP under acidosis (n = 6, P < 0.01). These results suggest that acidosis impairs the contractile response of cavernous smooth muscle to erectolytic agents. It may be the results of the interference by [H+] with the intra and extracellular mechanisms that regulate the homeostasis of [Ca2]. Conclusively, besides hypoxia, acidosis is another limiting factor of trabecular smooth muscle contractility like in ischemic priapism.

Prostate-specific antigen adjusted for the transition zone volume versus free-to-total prostate-specific antigen ratio in predicting prostate cancer

BACKGROUND

We performed this study to assess the efficacy of prostate-specific antigen adjusted for the transition zone volume (PSATZ) and free-to-total prostate-specific antigen (PSA) ratio (F/T ratio) in predicting prostate cancer in men with intermediate PSA levels of 4.1-10.0 ng/mL.

METHODS

Between March 1997 and September 1998, PSATZ was obtained from 67 patients who underwent ultrasonography guided systemic sextant biopsies and had a PSA of 4.1-10.0 ng/mL. PSATZ was compared with F/T ratio via receiver operating characteristic (ROC) curves.

RESULTS

Of 67 patients, 22 (32.8%) had prostate cancer and 45 (67.2%) had benign prostatic hyperplasia (BPH) on pathologic examination. Mean PSA, PSA density, F/T ratio and PSATZ were 7.96+/-2.01ng/mL, 0.28+/-0.14 ng/mL/cc, 0.10+/-0.06 and 0.70+/-0.28 ng/mL/cc in patients with prostate cancer and 6.39+/-1.68 ng/mL, 0.16+/-0.06 ng/mL/cc, 0.15+/-0.05 and 0.29+/-0.10 ng/mL/cc in patients with BPH, respectively. The ROC curve analysis demonstrated that PSATZ predicted the biopsy outcome significantly better than F/T ratio in all 67 patients (P<0.01) and in a subset of 53 men with normal digital rectal examination (P<0.01). With a cut-off value of 0.35 ng/mL/cc, PSATZ had a sensitivity of 86% and a specificity of 89% for predicting prostate cancer.

CONCLUSIONS

These results suggest that PSATZ and F/T ratio may be useful in diagnosing prostate cancer with intermediate levels of PSA. Prostate-specific antigen adjusted for the transition zone volume is more accurate than F/T ratio in distinguishing benign prostatic disease from prostate cancer. But large prospective studies are required to assess the precise role of PSATZ and F/T ratio in early prostate cancer detection.

Ethnic and gender differences and similarities in adolescent drug use and refusals of drug offers

This paper examines the relationship among ethnicity, gender, drug use, and resistance to drug offers among a sample of 2,622 African American, Mexican American, and White American seventh graders. A number of similarities were noted. First, these adolescents did not seem to possess large or sophisticated repertoires of offer resistance strategies. Second, most offers came from acquaintances in contrast to more intimate offers among older youths. Ethnic and gender differences were also noted. Ethnicity had significant effects on use and the offer process. Mexican Americans received more offers, used more drugs, and were more likely to be offered drugs by peer family members and at parties. European Americans were more likely to receive drug offers from acquaintances and at friends' homes and on the street. African Americans were more likely to receive offers from dating partners and parents, and in the park, and were more likely to resist offers of drugs-using explanations. Gender significantly affected drug offers and types of offers. Males were more at risk for offers and use at a younger age. Offers of drugs to males were more likely to come from parents or other males, while offers to females were more likely to come from other females or dating partners. Males also were more likely to receive drug offers that appeal to their social standing or self-image while females received either simple offers or those that minimize effects. Finally, offers of drugs to males were more likely to be made in public, while those to females were more likely to occur in private. Cultural explanations are offered for these findings.

A KATP-channel opener as a potential treatment modality for erectile dysfunction

OBJECTIVES

To assess the effects of pinacidil (a KATP-channel opener) for the treatment of penile erectile dysfunction and to examine the role of the K+-channel in cavernosal smooth muscle contractility.

MATERIALS AND METHODS

Using a feline model, the magnitude of penile erection caused by pinacidil was compared with that caused by erectogenic drugs, e.g. acetylcholine, prostaglandin E1 (PGE1) and L-arginine. The effects of K+-channel blockers (4-aminopyridine, glibenclamide and tetraethylammonium) and pinacidil on penile erections induced by the drugs were investigated.

RESULTS

The intra-arterial injection of pinacidil caused a dose-dependent increase in intracavernosal pressure (ICP) and the increase in ICP induced by pinacidil with acetylcholine, PGE1 or L-arginine was more pronounced than with the compounds alone. Furthermore, pinacidil (1 mmol/L) effectively reversed the inhibitory effects of the K+-channel blockers on the cavernosal relaxation induced by acetylcholine, PGE1 or L-arginine (P<0.01). Notably, pinacidil induced cavernosal relaxation after injecting the drugs even in cases refractory to higher concentrations (0.1 mol/L) of the drugs (n=11, P<0.01).

CONCLUSIONS

These results suggest that pinacidil is effective in relaxing feline erectile tissue in vivo, probably via increased K+ permeability and subsequent hyperpolarization. Further comparative studies with erectogenic compounds on human erectile tissue and clinical testing are required to determine whether K+-channel openers can be used in the diagnosis and treatment of erectile dysfunction. However, pinacidil seems promising as an intracavernosal agent combined with PGE1 to produce synergistic effects.

The role of nitric oxide in vivo feline erection under hypoxia

Previous in vitro studies have demonstrated that the cavernous relaxation under hypoxia does not involve the endothelium dependent mechanism. However, the mechanism of nitric oxide pathway under hypoxia are not fully evaluated or understood yet in vivo. The changes of intracavernous pressure to various vasoactive substances were monitored in 45 mature male cats in vivo under normoxia and hypoxia (pH: 7.03, PO2: 25.52 mmHg, PCO2: 84.66 mmHg). L-arginine and SNAP (s-nitroso-n-acetyl-penicillamine) produced cavernous relaxation under normoxia, but not under hypoxia (n = 19, P < 0.01). The L-arginine-induced relaxations were inhibited by L-NAME (N omega-nitro-1-arginine-methyl-ester) or methylene blue under normoxia (n = 19, P < 0.01). The cavernous relaxation was 58% suppressed under hypoxia compared to normoxia with 10(-3) M/0.2 ml of acetylcholine (n = 22, P < 0.01). Moreover, L-NAME attenuated the acetylcholine-induced relaxation under normoxia, but not under hypoxia (n = 22, P < 0.05). Epinephrine suppressed the acetylcholine-induced relaxation in both conditions (n = 10, P < 0.01), while indomethacin significantly potentiated the acetylcholine-induced relaxation under normoxia compared to hypoxia (n = 6, P < 0.05). However, none of these substances responded in severe hypoxia (PO2 < 15 mmHg, n = 3). These results suggest that erectile and contractile responses are attenuated under hypoxia. The endothelium derived relaxation via nitric oxide does not play a role in cavernous relaxation under definitive hypoxia with acidosis like in ischemic priapism (PO2 < 30 mmHg, pH < 7.25).

Fibronectin inhibition of platelet thrombus formation in an in vivo porcine model of vascular injury

Platelets adhere and aggregate in response to exposed subendothelial matrix during vascular injury. The present study examines the effect of plasma fibronectin on platelet deposition at a site of vascular injury in an in vivo porcine model. The internal carotid arteries in anesthetized Yorkshire pigs were bilaterally exposed and the distal half of each vessel stripped of endothelium. Following stripping, one in situ carotid artery preparation was filled with 0.5 mg/ml porcine plasma fibronectin and the other artery filled with vehicle solution, to serve as a control. After five minutes, 6-7 x 10(9) 111Indium-labeled autologous platelets were infused via a femoral vein cannula, and carotid blood flow was re-established for 20 minutes. The vessel segments were excised and deposition of platelets determined. Vascular stripping increased platelet deposition 52-fold, as compared to unstripped vessel segments. Fibronectin pretreatment did not affect platelet deposition in control vessel segments but decreased platelet deposition by 77% in stripped vessel segments. Transmission and scanning electron microscopy indicated that reduced platelet deposition in the fibronectin treated group was due to decreased platelet aggregation rather than decreased adhesion.

Stability of ciprofloxacin injection in peritoneal dialysis solutions

The stability of ciprofloxacin 25 mg/L in peritoneal dialysis solutions containing 1.5% and 4.25% dextrose after storage at 4 degrees C for two weeks, 25 degrees C for one week, or 37 degrees C for two days was evaluated. Ciprofloxacin 50 mg was added to 18 2-L bags of peritoneal dialysis solutions, nine containing 1.5% dextrose and nine containing 4.25% dextrose. Three bags of each dialysis solution were stored at 4 degrees C for 14 days, 25 degrees C for 7 days, and 37 degrees C for 2 days. Samples were drawn from each bag, and ciprofloxacin concentrations were measured by high-performance liquid chromatography. Stability was defined as less than 10% decrease from initial concentration. In the solution containing 1.5% dextrose, 87.2% of the ciprofloxacin remained after 14 days of storage at 4 degrees C, 93.4% remained after 7 days of storage at 25 degrees C, and 95.2% remained after 2 days of storage at 37 degrees C. In the solution containing 4.25% dextrose, 89.0% of the ciprofloxacin remained after 14 days of storage at 4 degrees C, 93.7% remained after 7 days of storage at 25 degrees C, and 97.8% remained after 2 days of storage at 37 degrees C. In peritoneal dialysis solutions containing 1.5% and 4.25% dextrose, ciprofloxacin was stable for seven days at 25 degrees C and for 48 hours at 37 degrees C. Ciprofloxacin concentrations after two weeks at 4 degrees C were below 90% of initial concentration.

Haemoglobin inhibition of fibrin polymerization and clotting

Clotting of human plasma by human alpha-thrombin was prolonged in the presence of haemoglobin as was human and bovine fibrinogen. Specifically, the clot time doubled for human plasma, human fibrinogen and bovine fibrinogen at 483, 233, and 116 microM haemoglobin, respectively. Fibrinopeptide A release was not inhibited at concentrations in approximately 16,000 molar excess compared with alpha-thrombin. Turbidometric analysis of fibrin polymerization showed a lengthening of the lag phase as well as the fibrin assembly process in the presence of haemoglobin. These findings suggested that neither fibrinogen recognition nor catalytic efficiency of thrombin was affected, implying that haemoglobin interferes with fibrin polymerization. Since human blood contains sufficient haemoglobin in erythrocytes to generate concentrations of up to 2.3 mM upon cell lysis, and haemoglobin concentrations of 0.16-0.48 mM caused 1.25 to two times longer clotting times in fresh human plasma, respectively, haemoglobin may act to modulate clot formation under conditions of haemolysis.

Organ distributions of liposome-loaded rat platelets

Past in vitro functional assays have demonstrated that platelet function is not inhibited by liposome uptake. In the present study, the organ distributions of control and liposome-loaded Sprague-Dawley rat platelets were examined to determine whether liposome uptake enhances RES uptake. Platelets were isolated using STRactan density gradient centrifugation, incubated with small unilamellar liposomes in vitro for 1 hour, labeled with 51Cr and injected into a cohort group of rats. One hour post-injection the spleen, liver, lungs, blood, kidneys and bladder contents were removed and the percentages of the recovered dose localized per total organ (%RD) were determined. The RES index, defined as %RDliver + %RDspleen, were 24.8 +/- 4.5 and 20.5 +/- 5.0 for the control platelets and liposome-loaded platelets, respectively. These results indicate that liposome uptake does not enhance RES uptake.

Effect of 13-hydroxyoctadeca-9,11-dienoic acid (13-HODE) on thrombin induced platelet adherence to endothelial cells in vitro

The effect of exogenous 13-HODE on alpha-thrombin induced adherence of platelets to monolayers of cultured pulmonary artery endothelial cells was determined using homologous sheep cells. In a separate series of experiments, endogenous 13-HODE was demonstrated in sheep endothelial cells by reverse phase high pressure liquid chromatography. Levels of endogenous 13-HODE were decreased by alpha-thrombin preincubation. Exogenous 13-HODE (10 microM) reduced the augmented platelet adherence produced by coincubation of alpha-thrombin with platelets and endothelial monolayers, and eliminated the enhancement of platelet adherence produced by preincubation of alpha-thrombin with endothelial monolayers. 13-HODE also reduced the alpha-thrombin induced adherence of platelets to monolayers pretreated with aspirin and to fixed monolayers indicating a direct effect of 13-HODE as opposed to secondary effects mediated by the release of prostacyclin (PGI2) or endothelial derived relaxing factor (EDRF). Platelet adherence to subendothelial matrix was also reduced by 13-HODE. 13-HODE inhibited platelet aggregation initiated by 0.2 U/ml alpha-thrombin but did not affect aggregation initiated by 2.0 U/ml alpha-thrombin. These data provide evidence for the ability of exogenous 13-HODE to attenuate the interaction of thrombin activated platelets with endothelial cells as well as with other platelets.

Thrombin-induced leukopenia and thrombocytopenia are attenuated by PAF antagonist WEB 2086

Thrombin has been shown to increase pulmonary transvascular permeability in vivo. This permeability change appears to be dependent on polymorphonuclear leukocytes (PMNs). In vitro, thrombin has been demonstrated to increase PMN adherence to endothelial cells coincident with generation of platelet activating factor (PAF) by endothelial cells. These observations have led to the suggestion that PAF mediates, in part, the attachment of PMNs to endothelial cells. We examined this hypothesis in vivo and in vitro with a specific PAF receptor antagonist, WEB 2086. Prior infusion of WEB 2086 into conscious sheep significantly attenuated the drop in peripheral blood PMN counts observed during and after infusion of alpha-thrombin (30 NIH U/kg). These data suggest that WEB 2086 prevented PMN margination on endothelial cells. WEB 2086 also attenuated the thrombocytopenia seen after thrombin infusion and ameliorated the thrombin-induced hypoxemia and hemoconcentration. WEB 2086 did not affect the thrombin-induced hemodynamic response, the degree of intravascular coagulation as assessed by fibrin degradation product generation, or thromboxane B2 generation. In vitro, WEB 2086 prevented the augmented adherence of sheep PMNs to sheep endothelial cell monolayers after thrombin stimulation. The results of the present study are consistent with the hypothesis that PAF mediates, at least in part, thrombin-induced leukopenia and thrombocytopenia in vivo.

Thrombin structure and function: why thrombin is the primary target for antithrombotics

Thrombin has both beneficial and harmful effects. In order of importance, at very low concentrations, alpha-thrombin firstly amplifies its own generation through the activation of factors V and VIII, which are the primary targets of antithrombotic agents. It secondly functions at the cellular level where, at low concentrations it activates platelets, and at higher concentrations, induces endothelial cell changes (e.g., shape changes, albumin transport release of plasminogen activators and other substances). It thirdly converts fibrinogen into clottable fibrin and becomes actively incorporated into the forming thrombus. In addition, it activates protein C, which in turn degrades factors V and VIII (and/or their activated forms) and causes the shutdown of thrombin generation. When compared to other serine proteinases of the blood coagulation and fibrinolytic systems, alpha-thrombin is unique in that it loses most of its proenzyme activation fragment and has developed multisite short-ranged bridge-binding interactions, which appear to explain thrombin specificity. To understand thrombin is to understand haemostasis.

Thrombin's enzymatic activity increases permeability of endothelial cell monolayers

Human alpha-thrombin increases the permeability of bovine pulmonary artery endothelial cell (CCL-209) monolayers. To determine if this increase is via an enzymatic or receptor-mediated mechanism, enzymatically active forms of alpha-thrombin and enzymatically inactive forms with cell binding activity were incubated with the monolayers. Enzymatic forms included alpha-thrombin and two digestion products, zeta-thrombin (chymotryptic product with 89% clotting activity) and gamma-thrombin (tryptic product). Enzymatically inactive forms included D-Phe-Pro-Arg-chloromethylketone-(PPACK) alpha-thrombin and diisopropylphosphorofluoridate-(DIP) alpha-thrombin. Cell binding activity of alpha- and PPACK-alpha-thrombin was demonstrated to be similar to each other and comparable to that cited in the literature for DIP-alpha-thrombin. gamma-Thrombin, on the other hand, did not compete for binding of 125I-labeled alpha-thrombin. All enzymatic forms of alpha-thrombin increased endothelial permeability as assessed by the clearance of 125I-albumin across the monolayers. Coincubation of PPACK, an enzymatic site inhibitor, with alpha- or gamma-thrombin prevented the increase in permeability, further indicating that alpha-thrombin increased permeability by its enzymatic activity. Both enzymatically inactive forms of alpha-thrombin with high-affinity binding activity had no effect on permeability. To further examine whether cell binding activity of alpha-thrombin contributed to the increased permeability, a sulfated COOH-terminal fragment of hirudin (hirugen) that binds to the anion-binding site of alpha-thrombin but, unlike hirudin, does not interact with the catalytic site was coincubated with alpha-thrombin.(ABSTRACT TRUNCATED AT 250 WORDS)

Electron microscopy of platelet interactions with heme-octapeptide-labeled fibrinogen

Binding of fibrinogen to ADP-activated platelets was visualized by labeling the molecule with heme-octapeptide (microperoxidase) for direct cytochemical staining. Transmission electron microscopy of the platelet aggregates showed most of the fibrinogen distributed widely over the platelet surface in nonbridging rims of 7- to 9-nm thickness. Short peroxidase-positive bridges (less than 25 nm) were found in clusters in regions of close contact between the platelets, but 50-nm bridging corresponding to the length of the molecule was not seen by this method. Thus the fibrinogen appeared to be binding in a predominantly prone rather then upright orientation on the platelets. Abundant 50-nm bridging seen by nonspecific staining appeared unrelated to the length of the fibrinogen molecule because the bridging did not change when the length of the fibrinogen was more than doubled by end-to-end cross-linking with factor XIIIa. It is suggested that the observed binding and bridging of fibrinogen in a prone orientation is promoted by the existence of multiple platelet-binding domains on the molecule.

Platelet modulation of neutrophil superoxide anion production

The effect of platelets on polymorphonuclear leukocytes (PMN) O2- production was examined using autologous sheep and human cell systems. Coincubation of sheep platelets with sheep PMNs in the absence of thrombin resulted in a significant inhibition in basal PMN O2- production. The platelet-derived inhibitory activity was released into the medium and could be destroyed by adenosine deaminase suggesting that the inhibitor was adenosine. Addition of alpha-thrombin or platelet activating factor (PAF) enhanced PMN O2- production but only when platelets were present. The enhancement of O2- production in response to thrombin was dependent upon the thrombin concentration and the platelet-PMN ratio. With a platelet: PMN ratio of 30: 1, addition of 10 nM thrombin to sheep cells resulted in a 5-fold increase in O2- production, whereas addition of 10 nM PAF caused a 2-fold increase in O2-. Addition of thrombin or PAF to either PMNs or platelets by themselves did not initiate an increase in O2- generation. The response of human cells was similar except that both thrombin and PAF triggered a 2-fold increase in PMN O2- production in the presence of platelets. The platelet-derived enhancement activity was not released into the medium and was not blocked by WEB 2086, NDGA, ETYA, aspirin or adenosine deaminase. The enhancement effect appeared to be localized to the platelet membrane and we believe requires platelet-PMN contact.

Platelet activating factor and sheep platelets: a sensitive new bioassay

The in vitro response of sheep platelets to platelet activating factor (PAF) was investigated. Sheep platelet-rich plasma aggregated in response to PAF with an EC50 of 10 nM. Platelets isolated via arabinogalactan density gradient centrifugation displayed an EC50 of 50 pM with a threshold response at 0.1 pM. PAF-induced release of 14C-serotonin from isolated sheep platelets was comparable with an EC50 of 50 pM and threshold release at 10 fM. PAF-induced aggregation was specific in that it could be blocked by the competitive receptor antagonists Alprazolam (Upjohn, IC50 = 40 microM), L-652,731 (MSD, IC50 = 6 microM), and WEB 2086 (Boehringer Ingelheim, IC50 = 0.8 microM). At micromolar concentrations, WEB 2086 did not inhibit ADP- or thrombin-induced aggregation nor thrombin-induced serotonin release. However, at higher concentrations of WEB 2086 some inhibition of thrombin-induced platelet aggregation and release was observed. Subsequent experiments demonstrated that high concentrations of WEB 2086 can inhibit thrombin-induced clotting (Ki = 866 microM) and cleavage of the chromogenic substrate Spectrozyme-TH (Ki = 842 microM). In summary, the response of isolated sheep platelets to PAF was specifically inhibitable and was 10 to 100 times more sensitive than washed rabbit platelets, the most popular bioassay currently in use.

Endothelin-like pulmonary vasoconstrictor peptide release by alpha-thrombin

The endothelial cells lining the vessel wall can modulate vasomotor tone by releasing vasoactive factors, such as endothelial-derived constricting factors. We observed that alpha-thrombin, but not catalytically inactivated alpha-thrombin, mediated the release of two pulmonary vasoconstrictor peptides into the venous effluent of guinea pig lungs. These peptides elicited a slow-onset, long-lasting pulmonary vasoconstriction similar to the effect of endothelin, an endothelial-derived 21-amino acid vasoconstrictor peptide previously isolated from cells in culture. One of the isolated peptides coelutes with endothelin upon reverse-phase HPLC with an acetonitrile gradient and has a molecular weight comparable to endothelin as determined by gel-permeation HPLC. The other vasoconstrictor peptide elutes earlier than endothelin on reverse-phase HPLC and exhibits a lower molecular weight. The studies show the release of endothelin-like pulmonary vasoconstrictor peptides in the intact lung by alpha-thrombin, a central regulatory enzyme in hemostasis.

Isoproterenol reduces thrombin-induced pulmonary endothelial permeability in vitro

The ability of the beta-adrenergic agonist, isoproterenol, to attenuate the thrombin-induced increase in endothelial permeability was examined by measuring 125I-labeled albumin clearance across endothelial cell monolayers. Bovine pulmonary artery endothelial cells (CCL-209) were grown to confluence on gelatinized, polycarbonate micropore filters and mounted on modified Boyden chambers with Dulbecco's modified Eagle's medium (DMEM) and 0.5% bovine serum albumin. alpha-Thrombin at 0.2 nM to 2 microM produced a dose-related increase (P less than 0.01) in 125I-labeled albumin clearance from the DMEM control value. Light and electron microscopy revealed that the thrombin-induced increase in permeability correlated with changes in cell shape and rearrangement of filamentous actin. Coincubation of 2 microM isoproterenol with 2 microM alpha-thrombin reduced (P less than 0.01) the thrombin-induced increase in albumin clearance and the observed morphological changes. This attenuation was not caused by inhibition of thrombin's enzymatically active site, since isoproterenol did not impair thrombin's fibrinogen clotting activity nor its amidolytic cleavage of an artificial substrate (Spectrozyme-TH). Coincubation of 20 microM propranolol, a beta-adrenergic antagonist, with 2 microM isoproterenol and thrombin blocked the permeability-decreasing effect of isoproterenol. Both 2 microM isoproterenol and 2 pM alpha-thrombin alone decreased (P less than 0.01) albumin clearance below the DMEM control value. These results suggest that isoproterenol can reduce the thrombin-induced increase in endothelial permeability in vitro by directly maintaining actin filaments and the shape of endothelial cells.

Platelets adhere to thrombin-treated endothelial cells in vitro

Interaction of thrombin with vascular endothelial cells was investigated as a mechanism promoting platelet activation and adherence to endothelial monolayers. We found that pretreatment of endothelium with alpha-thrombin in the absence of platelets results in the attachment of platelets to endothelial cells after the removal of fluid-phase alpha-thrombin. This activity was eliminated by exposure of alpha-thrombin-pretreated endothelial cells to active site inhibitors of alpha-thrombin or by adding alpha-thrombin in the presence of excess diisopropyl fluorophosphate-inhibited thrombin, suggesting retention of active alpha-thrombin by a receptor-mediated mechanism. Morphological data and the results of [14C]serotonin release studies indicate that platelets are activated by alpha-thrombin-pretreated endothelium and that adherence represents aggregates of activated platelets as well as individual platelets. Adherence on alpha-thrombin-pretreated endothelium is dependent on divalent cations. Platelets also adhered to aortic segments pretreated with thrombin. The data of the current studies support the contention that alpha-thrombin can promote adherence of activated platelets to endothelial cells because of the binding and retention of alpha-thrombin to endothelial cells in a manner in which it remains active and available for platelet activation.

Platelets decrease albumin permeability of pulmonary artery endothelial cell monolayers

Since platelets may modulate endothelial cell permeability, we examined the effects of platelets on 125I-albumin permeability of cultured bovine pulmonary artery endothelial cell monolayers. The experimental system consisted of endothelial cells grown to confluence on a gelatinized polycarbonate filter. We quantified the diffusive flux of 125I-albumin from luminal chamber to the abluminal chamber. Washed human platelets added to the monolayers decreased the albumin flux in a concentration-dependent manner, with a 65% decrease occurring at the highest concentration of platelets (5 x 10(7) platelets) added to the 700-microliters luminal chamber. In contrast, neither paraformaldehyde-fixed platelets nor fresh red blood cells changed 125I-albumin permeability. Platelets had no effect on 125I-albumin permeability across the gelatinized filters without endothelial cells present. Supernatants of platelet lysates also reduced albumin flux. The effect produced by intact platelets or platelet lysate was not influenced by the presence of ketanserin (a serotonin receptor antagonist), propranolol (a beta-adrenergic receptor antagonist), or aspirin (an inhibitor of cyclooxygenase). Platelets activated by thrombin did not produce an effect that was different from the effect produced by intact platelets. The activity of the supernatant of platelet lysate remained in the aqueous phase after ether extraction. The results indicate that the platelet-mediated decrease in endothelial cell permeability to 125I-albumin is the result of a hydrophilic platelet-derived factor(s) and not secondary to mechanical obstruction of endothelial "leaks" by the platelets.

Fibronectin augments binding of fibrin to macrophages

Because of the demonstrated ability of fibronectin to mediate particle uptake by macrophages and the demonstrated affinity of plasma fibronectin for fibrin, we investigated the ability of plasma fibronectin to augment macrophage binding of fibrin. Fibronectin significantly increased fibrin binding by elicited peritoneal macrophages and isolated hepatic Kupffer cells. The binding of fibrinogen was not augmented in the presence of fibronectin. The small amount of macrophage-associated fibrin observed in the absence of fibronectin was primarily internalized, whereas the increment in fibrin binding in the presence of fibronectin remained primarily surface bound, as indicated by susceptibility to removal by trypsin. An amino terminal fibrin-binding fragment of plasma fibronectin could similarly support binding of fibrin by peritoneal macrophages. Greater quantities of fibrin were associated with the macrophages in the presence of protease inhibitors, which inhibited elastase activity, but not in the presence of those that inhibited cathepsin activity, suggesting that an elastase-like protease may degrade surface-bound fibrin. Uptake of both fibrin and fibronectin was inhibited by prior treatment of cells with trypsin. Competitive binding studies suggested the presence of a high-affinity fibronectin receptor on peritoneal macrophages. Data from the current study thus support the conclusion that fibronectin augments binding of fibrin to the surface of mononuclear phagocytes.

The inhibitory effect of plasma fibronectin on collagen-induced platelet aggregation

Plasma fibronectin (Fn) has been proposed to have an antithrombotic effect, protecting against platelet and fibrinogen consumption after injury. The current study was designed to determine the effect of plasma fibronectin on collagen-induced platelet aggregation. In vitro aggregometry using an isolated homologous rat system, demonstrated a significant (P less than .05) inhibitory effect of 120 micrograms/mL Fn on platelet aggregation as induced by 60 micrograms/mL fibrillar collagen (type I). The inhibition was evidenced by a threefold increase in lag time and a significant decrease in the rate and extent of aggregation. The hypothesis was also tested using an in vivo model of collagen-induced platelet aggregation. The model used was intravenous injection of 2 mg/kg of homologous type I collagen into anesthetized Sprague-Dawley rats. Injection of collagen preincubated with 4 mg/kg Fn resulted in significantly less thrombocytopenia and fibrinogen consumption as compared with injection of collagen alone. The results of both the in vitro and in vivo studies are consistent with the proposed antithrombotic effect of plasma fibronectin.

Reticuloendothelial-depressing substance: studies on the mechanism of action

This study was carried out to evaluate the mechanism of action of a reticuloendothelial (RE)-depressing substance. This RE-depressing substance was obtained from the plasma of dogs subjected to 3 hr of intestinal ischemia. RE-depressing substance was partially purified by dialysis and reverse-phase column chromatography. The assay of RE-depressing activity was based on the depression of the rate of clearance of colloidal carbon from the blood of rats or mice. The effect of RE-depressing substance on three other RE system (RES) test particles (gelatinized lipid emulsion, formalinized sheep erythrocytes, and IgM-coated erythrocytes) was determined. RE-depressing substance did not affect the clearance rate or the organ localization of these three test particles. Therefore, RE-depressing substance affected only the clearance of colloidal carbon. Since platelet aggregation has been shown to contribute to the clearance of colloidal carbon, the effect of RE-depressing substance on platelet aggregation was evaluated. RE-depressing substance depressed in vitro platelet aggregation induced by ADP or collagen. It was concluded that the effect of RE-depressing substance on the clearance of colloidal carbon was due to a depression of platelet aggregation rather than to a depression of hepatic macrophage phagocytic function.

Depressed reticuloendothelial clearance of platelets in rats after trauma

Platelet microembolization may contribute to microcirculatory and organ damage following trauma and shock. It is hypothesized that posttraumatic reticuloendothelial depression predisposes to such microembolization by failure to clear altered platelets from the circulation. The present study evaluated the short-term (1 h) clearance and organ localization of radiolabeled homologous damaged platelets in normal rats and in rats following sublethal Noble-Collip drum trauma. Platelets were collected in citrated platelet-rich plasma from normal rats and labeled with 51Cr in citrated saline. Platelets were altered by repeated centrifugation in protein-free medium. These platelets differed functionally and morphologically from normal platelets. Disappearance of iv injected damaged platelets conformed to a two-compartment exponential clearance. Velocity of clearance in the rapid compartment correlated with hepatic platelet localization, whereas velocity of clearance in the second compartment correlated with splenic platelet localization. Clearance rate of the rapid compartment was depressed at 1 h after trauma and elevated at 24 h. These changes were associated with a decrease in hepatic platelet localization at 1 h and an increase above normal at 24 h. Splenic platelet localization was decreased by 3 h following trauma. Pulmonary platelet localization was increased at all times following trauma. It is concluded that the posttrauma state is associated with a defect in the reticuloendothelial system clearance of altered platelets, which may augment embolization of platelets in the lung.

Influence of plasma fibronectin on the response to infusion of thrombin and adenosine diphosphate

An important physiological anti-thrombotic function has been suggested for plasma fibronectin and the reticuloendothelial system. The current study evaluated the effects of specific immunological fibronectin depletion and fibronectin supplementation upon resistance to infusion of thrombin and ADP in terms of mortality, mean arterial blood pressure and circulating levels of platelets, fibrinogen and fibrin degradation products. Mortality data indicated that rats with reduced fibronectin levels had reduced resistance to thrombin or adenosine diphosphate infusion. The increased lethality was characterized by reduced circulating levels of fibrinogen and platelets while fibrin degradation product levels rose. The infusion of ADP or thrombin in fibronectin supplemented rats failed to elicit higher mortality or reduce fibrinogen or platelet levels further. These data are consistent with the hypothesis that resistance to excessive coagulation and/or platelet aggregation is correlated to circulating plasma fibronectin levels. It is suggested that by direct effects and/or acting as an opsonin for RES phagocytosis, plasma fibronectin acts as an important anti-thrombotic mechanism.