Spheroid architecture strongly enhances miR-221/222 expression and promotes oxidative phosphorylation in an ovarian cancer cell line through a mechanism that includes restriction of miR-9 expression

BACKGROUND

Tumor cell spheroids are organized multicellular structures that form during the expansive growth of carcinoma cells. Spheroids formation is thought to contribute to metastasis by supporting growth and survival of mobile tumor cell populations.

METHODS AND RESULTS

We investigated how spheroid architecture affects OXPHOS activity, microRNA expression, and intraperitoneal survival of an ovarian carcinoma cell line using high resolution respirometry, quantitative RT-PCR, and a rodent intraperitoneal growth model. Rates of oxidative phosphorylation/respiration per cell of cells growing as spheroids were nearly double those of a variant of the same cell type growing in suspension as loosely aggregated cells. Further, inhibition of spheroid formation by treatment with CDH2 (N-cadherin) siRNA reduced the rate of OXPHOS to that of the non-spheroid forming variant. Cells growing as spheroids showed greatly enhanced expression of miR-221/222, an oncomiR that targets multiple tumor suppressor genes and promotes invasion, and reduced expression of miR-9, which targets mitochondrial tRNA-modification enzymes and inhibits OXPHOS. Consistent with greater efficiency of ATP generation, tumor cells growing as spheroids injected into the nutrient-poor murine peritoneum survived longer than cells growing in suspension as loosely associated aggregates.

CONCLUSIONS

The data indicate that growth in spheroid form enhances the OXPHOS activity of constituent tumor cells. In addition, spheroid architecture affects expression of microRNA genes involved in growth control and mitochondrial function. During the mobile phase of metastasis, when ovarian tumor cells disperse through nutrient-poor environments such as the peritoneum, enhanced OXPHOS activity afforded by spheroid architecture would enhance survival and metastatic potential.

Chronic shedding of a SARS-CoV-2 Alpha variant in wastewater

BACKGROUND

Central Michigan University (CMU) participated in a state-wide SARS-CoV-2 wastewater monitoring program since 2021. Wastewater samples were collected from on-campus sites and nine off-campus wastewater treatment plants servicing small metropolitan and rural communities. SARS-CoV-2 genome copies were quantified using droplet digital PCR and results were reported to the health department.

RESULTS

One rural, off-campus site consistently produced higher concentrations of SARS-CoV-2 genome copies. Samples from this site were sequenced and contained predominately a derivative of Alpha variant lineage B.1.1.7, detected from fall 2021 through summer 2023. Mutational analysis of reconstructed genes revealed divergence from the Alpha variant lineage sequence over time, including numerous mutations  in the Spike RBD and NTD.

CONCLUSIONS

We discuss the possibility that a chronic SARS-CoV-2 infection accumulated adaptive mutations that promoted long-term infection. This study reveals that small wastewater treatment plants can enhance resolution of rare events and facilitate reconstruction of viral genomes due to the relative lack of contaminating sequences.

SARS-CoV-2 wastewater monitoring in rural and small metropolitan communities in Central Michigan

Central Michigan University (CMU) participated in a state-wide SARS-CoV-2 wastewater monitoring program throughout the 2021-2022 academic year. Wastewater samples were collected weekly from ten on-campus sites and nine off-campus wastewater treatment plants servicing small metropolitan and rural communities. SARS-CoV-2 genome copies were quantified using droplet digital PCR. Case data reported by Central Michigan District Health Department and CMU were collected and compared with wastewater data. During the delta wave, wastewater detection and on-campus case reports increased rapidly with the start of the academic semester and peaked quickly, compared with a more gradual and prolonged increase in detection and case reports off-campus. During the omicron wave, transmission dynamics were similar on-campus and off-campus. Normalization of on-campus and off-campus wastewater data with pepper mild mottle virus gene expression suggested lower SARS-CoV-2 shedding per person in on-campus compared to off-campus samples during the delta wave, but no difference in virus shedding during the omicron wave. We discuss the possibility that a higher on-campus vaccination rate may have reduced virus shedding per person during the delta wave, but that this effect was lost with the omicron variant. This study suggests that wastewater monitoring is effective in rural and small metropolitan communities when used in conjunction with case reports to understand regional transmission dynamics and the impact of public health policies at a public university on virus shedding in the community.

Entecavir competitively inhibits deoxyguanosine and deoxyadenosine phosphorylation in isolated mitochondria and the perfused rat heart

Deoxyguanosine kinase (dGK) is reported responsible for the phosphorylation of deoxyadenosine (dA) and deoxyguanosine (dG) in the mitochondrial purine salvage pathway. Antiviral nucleoside analogs known as nucleoside reverse transcriptase inhibitors (NRTIs) must be phosphorylated by host enzymes for the analog to become active. We address the possibility that NRTI purine analogs may be competitive inhibitors of dGK. From a group of such analogs, we demonstrate that entecavir (ETV) competitively inhibited the phosphorylation of dG and dA in rat mitochondria. Mitochondria from the brain, heart, kidney, and liver showed a marked preference for phosphorylation of dG over dA (10-30-fold) and ETV over dA (2.5-4-fold). We found that ETV inhibited the phosphorylation of dG with an IC50 of 15.3 ± 2.2 μM and that ETV and dG were both potent inhibitors of dA phosphorylation with IC50s of 0.034 ± 0.007 and 0.028 ± 0.006 μM, respectively. In addition, the phosphorylation of dG and ETV followed Michaelis-Menten kinetics and each competitively inhibited the phosphorylation of the other. We observed that the kinetics of dA phosphorylation were strikingly different from those of dG phosphorylation, with an exponentially lower affinity for dGK and no effect of dA on dG or ETV phosphorylation. Finally, in an isolated heart perfusion model, we demonstrated that dG, dA, and ETV were phosphorylated and dG phosphorylation was inhibited by ETV. Taken together, these data demonstrate that dGK is inhibited by ETV and that the primary role of dGK is in the phosphorylation of dG rather than dA.

Changes in Nup62 content affect contact-induced differentiation of cultured myoblasts

Differentiation of cultured skeletal myoblasts is induced by extrinsic signals that include reduction in ambient mitogen concentration and increased cell density. Using an established murine myoblast cell line (C2C12), we have found that experimental reduction of the nucleoporin p62 (Nup62) content of myoblasts enhances differentiation in high-mitogen medium, while forced expression of Nup62 inhibits density-induced differentiation. In contrast, differentiation of myoblasts induced by low-mitogen medium was unaffected by ectopic Nup62 expression. Further analyses suggested that Nup62 content affects density-induced myoblast differentiation through a mechanism involving activation of p38 MAP kinase. Nuclear pore complex (NPC) composition, in particular changes in NUP62 content, may be altered during viral infection, differentiation, and in neoplastic growth. The results support a functional role for changes in Nup62 composition in NPCs and density-induced myogenic differentiation, and suggest a link between loss of Nup62 content and induction of an intracellular stress signaling pathways.

Irreversible lower limb ischaemia following ligation of the inferior mesenteric artery in the surgical treatment of rectal cancer

Rectal cancer and cardiovascular disease are both commoner in the elderly and may coexist. In some severe arteriopaths the blood supply to the lower limbs may be a collateral circulation from the inferior mesenteric artery. Patients with aorto-iliac occlusion or severe stenosis may have collaterals from the inferior mesenteric artery to the lower limb blood vessels. Ligation of the inferior mesenteric artery in treating rectal cancer can result in irreversible ischaemia as outlined in this report. Routine palpation of the femoral pulses and awareness of collateral circulation may avoid the disastrous consequences seen in the two cases described.

Neuroendocrine effects of d-fenfluramine and bromocriptine following repeated smoked cocaine in humans

To study the consequences of repeated smoked cocaine use on central serotonergic and dopaminergic function, the effects of d-fenfluramine (d-FEN) and bromocriptine on plasma hormones were determined at three time-points following repeated cocaine self-administration under carefully controlled conditions. In a 20-day inpatient study, male cocaine abusers (d-FEN: n=10; bromocriptine: n=8) self-administered smoked cocaine (12-50 mg) for 3 days followed by 2 weeks of abstinence. The acute effects of d-FEN (0 or 30 mg po) or bromocriptine (0 or 1.25 mg po) on plasma neuroendocrine levels were determined 1-2, 7-8, and 13-14 days after the last cocaine dose. Blood was drawn before and then every 30-60 min for 4 h after capsule administration. The effects of d-FEN and bromocriptine were also determined in healthy, outpatient controls; d-FEN was removed from medical use in the US midway through the study due to complications associated with chronic administration, so all of the control participants were tested in Italy. Cocaine users had a blunted prolactin and cortisol response to d-FEN that lasted for at least 2 weeks of cocaine abstinence, but had a normal response to bromocriptine, which suppressed prolactin by 50% of baseline. The long-lasting and selective disruptions in serotonin pathways following chronic cocaine use may provide a neurochemical basis for changes in mood commonly reported during cocaine withdrawal.

The NMDA antagonist memantine attenuates the expression of opioid physical dependence in humans

RATIONALE

Preclinical observations suggest that NMDA receptor-mediated glutamatergic neurotransmission is involved in the expression and maintenance of opioid dependence.

OBJECTIVE

The present study evaluated whether memantine, the clinically available non-competitive NMDA receptor antagonist, decreases naloxone-precipitated withdrawal in morphine-dependent humans.

METHODS

Eight heroin-dependent, non-treatment seeking, inpatient participants were stabilized on a fixed dose of morphine (30 mg PO qid). Subsequently, they received a series of challenges with naloxone (0.4 mg, IM) and the severity of opioid withdrawal was monitored. Either placebo or memantine (60 mg PO) was given 6 h before each naloxone challenge. A modified multiple baseline, across-participants design was used to evaluate the effects of memantine on the severity of naloxone-precipitated opioid withdrawal.

RESULTS

Naloxone increased ratings and produced physical changes consistent with opioid withdrawal. Memantine attenuated the severity of opioid withdrawal as assessed with the Clinical Institute for Narcotic Withdrawal Scale scale. Withdrawal was significantly reduced when naloxone was administered at 6 and 52 h after memantine, but not when administered 126 h (5 days) after memantine. Medication effects, assessed 5 h after memantine administration and before naloxone administration, included significant increases in ratings of "strong" and "good" drug effect, and "I feel sedated", "mellow", and "high".

CONCLUSIONS

Memantine attenuated the expression of opioid physical dependence in humans, indicating that glutamatergic neurotransmission at the NMDA receptor site contributes to the maintenance of opioid dependence. This finding suggests that memantine may be a useful adjunct in the treatment of opioid dependence.

Methamphetamine self-administration by humans

RATIONALE

Methamphetamine abuse has become increasingly problematic. Yet, the reinforcing effects of methamphetamine in humans have not been systematically evaluated.

OBJECTIVE

To characterize methamphetamine's reinforcing effects in human research participants under controlled laboratory conditions.

METHODS

Eight healthy research volunteers (one female, seven males) completed this 20-day residential study. On days 1, 5, 9, 13 and 17, at 1000 hours, participants received the "sample" oral dose of methamphetamine (0, 5, 10 mg) that was available for the next 3 days and they also received an alternative reinforcer, a $1 voucher (redeemable for cash at study's end). Over a 3-day period, volunteers participated in an eight-trial choice procedure, during which they had the opportunity to self-administer the dose of methamphetamine they most recently sampled or to receive the $1 voucher.

RESULTS

Participants' choice to self-administer methamphetamine significantly increased when active methamphetamine (5 mg and 10 mg) was available compared to placebo. No difference of choice was noted between low-dose and high-dose methamphetamine. However, the sampled 10 mg methamphetamine dose significantly increased several "positive" subjective ratings including "High," "Good Drug Effect," and "Stimulated," whereas the sampled 5 mg methamphetamine dose did not. Both active methamphetamine doses caused significant reductions in daily total caloric intake, relative to the respective placebo conditions.

CONCLUSION

These data demonstrate that oral methamphetamine is a positive reinforcer in humans.

Effects of ecopipam, a selective dopamine D1 antagonist, on smoked cocaine self-administration by humans

RATIONALE

Data obtained in laboratory animals and humans suggest that dopamine D1 receptor antagonists decrease cocaine self-administration and block cocaine's discriminative stimulus and subjective effects.

OBJECTIVES

This study investigates the effects of the selective dopamine D1 antagonist, ecopipam (SCH 39166), on the reinforcing, cardiovascular, and subjective effects of cocaine in humans.

METHODS

Ten non-treatment-seeking cocaine smokers (two females, eight males), residing on an inpatient research unit, were maintained on placebo and ecopipam (100 mg p.o.) in random order using a within-subjects, cross-over design. Cocaine self-administration (0, 12, 25, and 50 mg) was tested beginning on the 5th day of each 8-day maintenance condition. A six-trial choice procedure (cocaine vs $5 merchandise vouchers) was utilized, with sessions consisting of one sample trial, when participants smoked the cocaine dose available that day, and five choice trials, when participants chose between smoking the available cocaine dose or receiving one merchandise voucher.

RESULTS

In the presence of placebo cocaine, ecopipam significantly decreased cocaine craving while increasing alcohol and tobacco craving. In the presence of active cocaine, ecopipam increased cocaine self-administration (12 mg) and increased ratings of "good drug effect," "high," "stimulated," and dose quality (25 and 50 mg). Ecopipam produced small but significant increases in blood pressure, regardless of cocaine dose.

CONCLUSIONS

Maintenance on the long-acting dopamine D1 antagonist, ecopipam, enhanced both cocaine self-administration as well as its subjective effects compared to maintenance on placebo. These data suggest that chronic antagonism of the dopamine D1 receptor may not be a useful approach for the treatment of cocaine abuse.

Effects of repeated oral methamphetamine administration in humans

RATIONALE

Although methamphetamine use has increased over the past several years, few studies have evaluated the effects of repeated methamphetamine administration in humans.

OBJECTIVES

Because methamphetamine is often taken in a pattern of repeated use followed by a period of abstinence, the present study sought to evaluate the effects of repeated methamphetamine administration in humans. The hypothesis was that tolerance would develop to methamphetamine's effects.

METHODS

Seven normal, healthy volunteers participated in a 15-day residential study. Participants completed subjective-effects questionnaires and psychomotor performance tasks repeatedly throughout the experimental day. Oral methamphetamine (5, 10 mg BID) was administered on days 4-6 and 10-12; placebo was administered on all other study days.

RESULTS

Relative to placebo baseline, only two "positive" subjective ratings ("I feel a good drug effect" and "I feel high") were significantly elevated, and only on the 1st day of methamphetamine administration. In contrast, numerous "negative" ratings, including "I feel..." "a bad drug effect," "dizzy," and "flu-like symptoms" were elevated on the 3rd day of methamphetamine administration. Total caloric intake decreased and sleep was disrupted after methamphetamine administration, relative to baseline.

CONCLUSIONS

The pattern of methamphetamine's positive subjective effects were altered with chronic administration such that tolerance, or a decreased effect, occurred after repeated administration. In contrast, methamphetamine's negative subjective effects increased over days. These results suggest that in this population of normal volunteers, the abuse liability of oral methamphetamine is relatively low.

Bupropion SR worsens mood during marijuana withdrawal in humans

RATIONALE

Symptoms of withdrawal after daily marijuana smoking include increased ratings of irritability and depression. Similar mood symptoms are reported by cigarette smokers during nicotine abstinence.

OBJECTIVE

Given the successful use of sustained-release bupropion in treating nicotine dependence, this study investigated how maintenance on bupropion influenced symptoms of marijuana withdrawal compared to maintenance on placebo.

METHODS

Marijuana smokers (n=10) were maintained outpatient on active (300 mg/day) or placebo (0 mg/day) bupropion for 11 days, and were then maintained inpatient on the same bupropion dose for 17 days. For the first 4 inpatient days, participants smoked active marijuana [2.8% delta9-tetrahydrocannabinol (THC)] 5 times/day. For the remaining inpatient days, participants smoked placebo marijuana (0.0% THC) 5 times/day. Participants were then maintained outpatient on the alternate dose of bupropion for 11 days, followed by a second inpatient residential stay, paralleling the first. Medication administration was double-blind. Mood, psychomotor task performance, food intake, and sleep were measured daily during each inpatient phase. The order of active and placebo bupropion maintenance was counterbalanced between groups.

RESULTS

Bupropion had few behavioral effects when participants smoked active marijuana. During placebo marijuana smoking, i.e., active marijuana withdrawal, ratings of irritability, restlessness, depression, and trouble sleeping were increased by bupropion compared to placebo maintenance.

CONCLUSIONS

These data suggest that bupropion does not show promise as a potential treatment medication for marijuana dependence.

Blockade of cocaine-induced increases in adrenocorticotrophic hormone and cortisol does not attenuate the subjective effects of smoked cocaine in humans

Surgical or pharmacological ablation of the hypothalamic-pituitary-adrenal (HPA) axis reduces the discriminative stimulus and reinforcing effects of cocaine in laboratory rodents. We have recently reported that attenuation of cocaine-induced increases in cortisol does not modulate the subjective effects of smoked cocaine in humans. To examine whether attenuation of HPA function at the pituitary level reduces the effects of cocaine in humans, eight 'crack' cocaine abusers were pre-treated with the synthetic glucocorticoid, dexamethasone (0 and 2 mg), 10 h before receiving cocaine. Three doses of smoked cocaine (0, 12 and 50 mg) were administered in counterbalanced order under each pre-treatment condition. Dexamethasone alone increased heart rate and blood pressure, and completely abolished cocaine-induced adrenocorticotrophic hormone and cortisol release. Maximal heart rate following cocaine administration was significantly increased by dexamethasone. However, the subjective effects of cocaine were not affected by dexamethasone pre-treatment. These results extend our earlier findings with humans, indicating that the role of the HPA axis in mediating the effects of cocaine is limited. These data are concordant with findings in non-human primates, but contrast with findings in laboratory rodents, thus underscoring the importance of validation of rodent models with laboratory studies in humans.

Fluoxetine-maintained obese humans: effect on food intake and body weight

The effects of fluoxetine on food intake, body weight, and mood of obese individuals was examined in a 16-week inpatient/outpatient study. Six male and eight female obese volunteers began the study (four male and five females completed all phases of the study). They lived in a residential laboratory during three one-week inpatient periods separated by a 5-week and an 8-week outpatient period. Following an initial 4-day placebo baseline, participants were maintained on fluoxetine (60 mg/day) for the remainder of the study. Food intake parameters (total daily energy intake, macronutrient intake, mean number of eating bouts, interbout interval), body weight, subjective effects, and task performance were measured several times during the day during inpatient periods; food intake questionnaires were completed daily during the outpatient periods. Fluoxetine significantly reduced daily energy intake derived from fat, carbohydrate, and protein by decreasing the mean number of eating bouts per day throughout the study. No other food intake parameter was affected. Body weight was significantly reduced after 7 weeks, but not after 16 weeks of daily fluoxetine administration. These results indicate that fluoxetine reduced food intake for at least 16 weeks in nondepressed obese individuals without specifically affecting carbohydrate intake. Weight that was lost during the first few weeks of daily fluoxetine administration was subsequently regained even though food intake remained reduced. Therefore, fluoxetine maintenance does not appear promising as a sole long-term therapy for obesity.

Effect of a selective dopamine D1 agonist (ABT-431) on smoked cocaine self-administration in humans

RATIONALE

Data in laboratory animals suggest that D1 receptor agonists may have potential utility for the treatment of cocaine abuse.

OBJECTIVE

The effects of ABT-431, a selective agonist at the dopamine D1 receptor, on the reinforcing, cardiovascular and subjective effects of cocaine were investigated in humans.

METHOD

Nine experienced cocaine smokers (8M, 1F), participated in nine self-administration sessions while residing on an inpatient research unit: three doses of ABT-431 (0, 2, 4 mg i.v.) were each given in combination with three doses of smoked cocaine (0, 12, 50 mg). ABT-431 was intravenously administered over a 1-h period immediately prior to cocaine self-administration sessions. A six-trial choice procedure (cocaine versus $5 merchandise vouchers) was utilized, with sessions consisting of: (a) one sample trial, where participants received the cocaine dose available that day, and (b) five choice trials, where participants chose between the available cocaine dose and one merchandise voucher.

RESULTS

ABT-431 did not affect the number of times participants chose to smoke each dose of cocaine, but produced significant dose-dependent decreases in the subjective effects of cocaine, including ratings of "High," "Stimulated," dose liking, estimates of dose value, "Quality," and "Potency." Furthermore, there was a trend for ABT-431 (4 mg) to decrease cocaine craving. ABT-431 also increased heart rate, while decreasing systolic and diastolic pressure at each dose of cocaine.

CONCLUSIONS

These data suggest that D1 agonists may have potential utility for the treatment of cocaine abuse.

Abstinence symptoms following smoked marijuana in humans

Symptoms of withdrawal after oral delta9-tetrahydrocannabinol (THC) administration have been reported, yet little is known about the development of dependence on smoked marijuana in humans. In a 21-day residential study, marijuana smokers (n = 12) worked on five psychomotor tasks during the day (0915-1700 hours), and in the evening engaged in recreational activities (1700-2330 hours); subjective-effects measures were completed 10 times/day. Food and beverages were available ad libitum from 0830 to 2330 hours. Marijuana cigarettes (0.0, 1.8, 3.1% THC) were smoked at 1000, 1400, 1800, and 2200 hours. Placebo marijuana was administered on days 1-4 . One of the active marijuana doses was administered on days 5-8, followed by 4 days of placebo marijuana (days 9-12). The other concentration of active marijuana cigarettes was administered on days 13-16, followed by 4 days of placebo marijuana (days 17-20); the order in which the high and low THC-concentration marijuana cigarettes were administered was counter-balanced between groups. Both active doses of marijuana increased ratings of "High," and "Good Drug Effect," and increased food intake, while decreasing verbal interaction compared to the placebo baseline (days 1-4). Abstinence from active marijuana increased ratings such as "Anxious," "Irritable," and "Stomach pain," and significantly decreased food intake compared to baseline. This empirical demonstration of withdrawal from smoked marijuana may suggest that daily marijuana use may be maintained, at least in part, by the alleviation of abstinence symptoms.

Abstinence symptoms following oral THC administration to humans

Symptoms of dependence and withdrawal after the frequent administration of high doses (210 mg/day) of oral delta9-tetrahydrocannabinol (THC) have been reported, yet little is known about dependence on lower oral THC doses, more relevant to levels attained by smoking marijuana. In a 20-day residential study, male (n = 6) and female (n = 6) marijuana smokers worked on five psychomotor tasks during the day (0915-1700 hours), and in the evening engaged in private or social recreational activities (1700-2330 hours); subjective-effects measures were completed 10 times/day, and a sleep questionnaire was completed each morning. Food and beverages were available ad libitum from 0830 to 2330 hours. Capsules were administered at 1000, 1400, 1800, and 2200 hours. Placebo THC was administered on days 1-3, 8-11, and 16-19. Active THC was administered on days 4-7 (20 mg qid) and on days 12-15 (30 mg qid). Both active doses of THC increased ratings of "High," "Good Drug Effect," and "Willingness to Take Dose Again" compared to baseline (days 1-3). THC also increased food intake by 35-45%, and decreased verbal interaction among participants compared to placebo baseline. Tolerance developed to the subjective effects of THC but not to its effects on food intake or social behavior. Abstinence from THC increased ratings of "Anxious," "Depressed," and "Irritable," decreased the reported quantity and quality of sleep, and decreased food intake by 20-30% compared to baseline. These behavioral changes indicate that dependence develops following exposure to lower daily doses of THC than have been previously studied, suggesting that the alleviation of abstinence symptoms may contribute to the maintenance of daily marijuana use.

Ketoconazole attenuates the cortisol response but not the subjective effects of smoked cocaine in humans

Attenuation of hypothalamo-pituitary-adrenal (HPA) function in laboratory rodents has been found to reduce the reinforcing effects of cocaine. To examine whether attenuation of HPA function reduces the effects of cocaine in humans, one female and seven male 'crack' cocaine abusers were pretreated with three doses of ketoconazole (0, 600, 1200 mg), an inhibitor of adrenocorticoid biosynthesis, 1 h before receiving cocaine. Three doses of smoked cocaine (0, 12, 50 mg) were administered in counterbalanced order under each ketoconazole condition. Ketoconazole dose-dependently reduced cocaine-induced cortisol, but not adrenocorticotropin (ACTH) release, and attenuated the cocaine-induced increase in heart rate and blood pressure. Plasma ACTH levels were more predictive of blood pressure changes than either cocaine or cortisol levels. Suppression of cortisol secretion was not associated with a reduction in ratings of the subjective effects of cocaine. These results support a role for the HPA axis in the cardiovascular effects of cocaine, but do not support a role for the HPA axis in the subjective effects of cocaine. To the extent that self-administration can be predicted by subjective effects, these results further argue that the HPA axis does not play a critical role in cocaine self-administration by humans.

The effects of memantine on the subjective, reinforcing and cardiovascular effects of cocaine in humans

Eight male frequent cocaine smokers participated in a 44- to 47-day inpatient and outpatient study to assess the effects of the noncompetitive N-methyl-D-aspartate (NMDA) antagonist, memantine, on cocaine self-administration, subjective effects, and psychomotor performance. Participants were maintained on memantine (0 and 20 mg daily) for 7-10 days prior to laboratory testing, using a double-blind crossover design. Under each medication condition, participants smoked four doses of cocaine base (0, 12, 25 and 50 mg), and were subsequently given five opportunities, 14 min apart, to self-administer that dose of cocaine or receive a merchandise voucher ($5.00). Each cocaine dose was tested twice under each medication condition, and the order of medication condition and cocaine dose was systematically varied. Vital signs were recorded every 2 min, and subjective effects were assessed at baseline and after each cocaine or voucher delivery. In addition, psychomotor performance was assessed before and after each self-administration session. Memantine maintenance was not associated with changes in psychomotor performance or the number of cocaine doses chosen each session. Memantine maintenance was, however, associated with significant increases in some subjective effects of cocaine, including ratings of 'good drug effect', 'high', 'potency', 'quality', and street value. These data suggest that NMDA antagonists may have limited usefulness as treatment medications for cocaine abuse.

Effects of methysergide and loratadine on food intake, mood, and performance of humans living in a residential laboratory

The effects of loratadine, a peripherally acting histamine (H1) antagonist, and methysergide, a serotonin (5-HT) antagonist, were evaluated in seven normal-weight, male research volunteers, participating in a placebo-controlled, double-blind, 17-day residential study. Participants received oral loratadine (10 or 20 mg), methysergide (4 or 8 mg), or placebo at 1000 and 1700 hours daily. Active drug was administered on Days 4, 5, 7, 8, 11, 12, 15, and 16; placebo was administered on all other days. Drug and dose order were counterbalanced across participants. Food intake, performance, and subjective ratings were measured repeatedly throughout the day. Loratadine had no effect on food intake, performance, or subjective ratings. In contrast, total caloric intake significantly decreased from approximately 3500 kcal during placebo administration to 3065 kcal on the first but not the second day of methysergide administration. Consumption of carbohydrate (p < 0.055), protein, and fat decreased on the first day of methysergide administration. This decrease in food intake was due to a decrease in meal size; the number of meals consumed was not affected. The proportion of calories derived from carbohydrates significantly increased on the first day of methysergide administration. Methysergide also significantly impaired performance of a psychomotor task on the first day of high-dose administration and increased ratings of several subjective measures, including "Vomiting," "Stomach Pain," and "Miserable." These results suggest that the anorectic effect occurred as a result of the somatic and mood changes produced by methysergide. In addition, the inability of loratadine to affect food intake indicates that antagonism of central histamine receptors may be responsible for the increases in food intake produced by other antihistamines (e.g., diphenhydramine).

Binge cocaine self-administration by humans: smoked cocaine

Tolerance develops to the cardiovascular and subjective effects of intravenous cocaine during single self-administration sessions, but diminishes within 3 h after the session ends. To examine whether a similar pattern of tolerance occurs to smoked cocaine, seven adult 'crack' cocaine users completed a protocol investigating changes in behavior during the repeated self-administration of smoked cocaine. During sessions, participants could self-administer up to 6 doses of smoked cocaine (50 mg per dose), one every 14 min. Both two- and three-day binge conditions were tested. During the two-day binge, a 2.5 h cocaine self-administration session began at 1200 h and again at 1600 h on two consecutive days, while during the three-day binge, self-administration sessions occurred at 1200 h and 1600 h on three consecutive days. The first one or two cocaine doses in each session increased cardiovascular and subjective effects ratings; subsequent cocaine inhalations during the session did not increase these measures further, suggesting the development of acute tolerance to these effects. Ratings of 'I want cocaine' decreased slightly across three days of repeated smoked cocaine self-administration, while anxiety scores increased slightly across three days, suggesting that some effects of smoked cocaine may persist beyond a binge.

Effects of d-amphetamine on task performance and social behavior of humans in a residential laboratory

Six healthy adult male volunteers lived for 11 days in a residential laboratory. Acute effects of d-amphetamine (0, 5, or 10 mg/70 kg) on performance of tasks, social interaction, and self-reports of drug effects were measured. Each day, participants engaged in a 6.5-hr work period and a 6.5-hr recreation period. Beverages containing d-amphetamine or placebo were consumed daily before the work period and before the recreation period. d-Amphetamine increased response rate without affecting accuracy on some tasks. d-Amphetamine increased the proportion of time spent engaging in verbal interaction during the first but not the second week of study. No changes in self-reported drug effects were observed. Thus, d-amphetamine improved performance in the absence of stimulant-like subjective effects. This differentiation between performance and subjective effects confirms the importance of determining the effects of drugs on a range of behaviors.

Binge cocaine self-administration in humans: intravenous cocaine

Cocaine is frequently used in intermittent cycles of repeated dosing, or "binges." This pattern of cocaine use has been difficult to study in humans because currently available laboratory models use only one daily session during which a single dose or multiple doses are administered. In the present study, seven adult male IV cocaine users completed a protocol investigating changes in cardiovascular and subjective responses during the repeated self-administration of cocaine. Volunteers participated in a 2-day and a 3-day access condition. On each day of access, they participated in two 2.5-h sessions, one at 1200 and another at 1600 hours. In the 2- and 3-day conditions, participants had access to cocaine on 2 or 3 consecutive days, respectively. During sessions, participants could self-administer up to six doses of IV cocaine (32 mg/70 kg) every 14 min. Participants chose not to self-administer cocaine on only 10% of the 420 trials. Acute tolerance developed to the cardiovascular and several subjective effects of cocaine. Heart rate was the only measure that tended to decrease across days of repeated cocaine self-administration. Ratings of "I want cocaine" decreased at the end of the last self-administration session during both 2- and 3-day conditions. There was no difference between the 2- and 3-day conditions for any measure. The laboratory model of "binge" cocaine use established in this study can be used to describe changes in cardiovascular and subjective effects of cocaine within and between bouts of repeated cocaine use.

The effects of a monetary alternative on marijuana self-administration

The availability of alternative reinforcers can reduce drug self-administration. This 21-day residential study investigated the effect of monetary alternatives on marijuana self-administration. Three female and four male participants performed computer tasks (baseline) in the morning before smoking a sample marijuana cigarette (0.0, 1.8, or 3.9% delta 9-tetrahydrocannabinol (THC) and receiving the sample alternative ($5.00 voucher). In the afternoon, participants had five opportunities to choose either the marijuana cigarette sampled earlier or a voucher for $5.00. Participants were required to meet a criterion level of task performance to obtain each choice. The monetary performance criterion varied from day to day (80, 100, or 120% of baseline); the marijuana performance criterion remained constant at 100% of baseline. Choices were delivered in the evening, after task completion. Marijuana choice varied as a function of THC concentration and criterion to earn money. Active marijuana was always chosen more often than placebo, and active and placebo marijuana were chosen over money when the criterion to earn money was high. Task performance improved when criteria were imposed, even after participants had smoked the sample marijuana cigarette. Subjective ratings of drug effects increased with increasing THC concentration, but did not predict choice. The availability of a monetary alternative was effective in shifting choice to self-administer marijuana, and marijuana choice was sensitive to contingency manipulations. The results further indicate that contingency manipulations may override the performance-impairing effects of marijuana observed in other studies.

Factors influencing marijuana self-administration by humans

The self-administration of marijuana cigarettes varying in tetrahydrocannabinol (THC) content was measured by having participants choose between marijuana and an alternative reinforcer, i.e., snack food. Twelve marijuana users (eight men, four women), in groups of four, participated in a 16-day residential study. Each day, participants had the opportunity to choose repeatedly between a marijuana cigarette and a snack. The THC concentration of the cigarette changed each day (0.0, 2.2 or 3.9% delta 9-THC w/w), as did the number of snack items (one or two); each THC concentration was compared to each snack condition twice. Days were divided into a work period (09.15-16.45 h), comprising performance and subjective-effects tasks, and a recreation period (17.15-23.30 h). Each day at 10.00 h, participants "sampled" a marijuana cigarette containing the delta 9-THC concentration available that day, and selected the number of snack items available that day. Six "choice" trials occurred from 14.00-19.00 h, when participants responded under a modified progressive ratio schedule for either marijuana or snacks. At 18.15 h, participants could participate in a 10-min math task, in which each correct answer earned $1.00. Cigarettes containing 2.2 or 3.9% delta 9-THC were self-administered more often than placebo. The only other factor influencing marijuana choice was the opportunity to earn additional money, with participants choosing not to smoke immediately before the math task. By the end of the study, active marijuana had smaller effects on ratings of "high", "stimulated," and "good drug effect." These data demonstrate that: (a) delta 9-THC is an essential reinforcing component of marijuana; (b) marijuana use may be manipulated by monetary contingencies; and (c) tolerance may develop more readily to marijuana's subjective effects than its reinforcing effects.

Variations in cocaine self-administration by inbred rat strains under a progressive-ratio schedule

This study investigated the influence of genetics on extent of cocaine taking in rats that were self-administering cocaine under a progressive-ratio schedule. Fischer 344, ACI and Brown Norway rats were subjects because previous genetic studies on dopamine receptor loci have indicated that these are genetically divergent strains. All subjects were assessed for acquisition and stability of cocaine self-administration under a progressive ratio schedule. Subsequently, a dose-effect curve for cocaine self-administration was determined for each strain. Fischer 344 rats maintained a higher average breaking point than did the ACI or Brown Norway strains. In addition, dopamine receptor antagonists differentially reduced the ability of cocaine to serve as a reinforcer across the three strains. The D1-selective dopamine receptor antagonist, SCH 23390, and the D2/D3-selective dopamine receptor antagonist, eticlopride were significantly more effective in reducing the self-administration of cocaine in Brown Norway rats than for the other two strains. The results of this study demonstrate that genetic differences may play an important role in determining responding under progressive-ratio schedules for cocaine, possibly due to differences in the reinforcing efficacy of cocaine.

Arteriovenous fistulae complicating orthopaedic procedures

Arterial injuries in general and arteriovenous fistulae in particular are uncommon complications of orthopaedic procedures. We report the case of a 75 year old patient who suffered an arteriovenous fistula following bone graft insertion for an un-united tibial fracture. Aetiology diagnosis and management of these potentially serious injuries are reviewed.

Peripheral thrombolysis with tissue plasminogen activator. Results of two treatment regimens

OBJECTIVE

The purpose of this study was to document the response to tissue plasminogen activator given as either a low-dose intra-arterial infusion or a bolus infusion in patients with peripheral arterial or bypass graft occlusion.

DESIGN

Fifty thrombolytic procedures were carried out in 45 patients with a recent occlusion of a peripheral artery (41) or bypass graft (nine). A continuous infusion of 1.0 mg/h of tissue plasminogen activator was used in 27 patients (group A), while 23 patients were given a 20-mg bolus followed by an infusion of 1.0 mg/h (group B). Patients in the two groups were followed up for 12.1 +/- 9.3 months and 11.1 +/- 9.1 months, respectively.

RESULTS

In group A, the angiographic lysis rate was 74% and clinical success rate was 67%. In group B, the comparable rates were 70% and 48%. Lysis was quicker when a bolus infusion was used, the mean lysis time being 14.4 +/- 7.9 hours compared with 26.7 +/- 9.4 hours following infusion alone (P = .0005). There was one instance of major hemorrhage in group A and eight in group B (P = .0022), including two patients with cerebral hemorrhage, one of whom died.

CONCLUSION

Low-dose tissue plasminogen activator infusion is safe and reasonably effective, although a long treatment time is required. A bolus infusion regimen speeds lysis but is attended by a high incidence of serious hemorrhage.

Thrombolysis with tissue-plasminogen activator: results with a high-dose transthrombus technique

PURPOSE

Low-dose intraarterial tissue plasminogen activator (t-PA) is effective in peripheral thrombolysis but treatment time is prolonged. The aim of this study was to determine whether a transthrombus bolus of t-PA before low-dose infusion shortens lysis time.

METHODS

Twenty-three patients with peripheral arterial or bypass graft occlusion were treated with an initial bolus of 20 mg t-PA followed by a continuous infusion of 1 mg/hr.

RESULTS

Angiographic lysis was achieved in 16 patients (70%) with a mean time to complete lysis of 14.4 +/- 7.9 hours. Two patients had reocclusion on days 1 and 3, respectively. There were three deaths within the first week of treatment, one from cerebral hemorrhage and two from myocardial infarction. A clinically successful outcome was achieved in 11 patients (48%). Those patients with patency at 1 week maintained this response at a mean follow-up of 11.7 +/- 9.1 months. Thrombolysis was unsuccessful in seven instances. In three of these cases the infusion had to be discontinued prematurely because of serious hemorrhage. Of the seven unsuccessful cases, three patients subsequently underwent a femorodistal bypass, two were left with tolerable ischemic symptoms, and two required a major amputation. There were eight major bleeding complications (35%), four at or adjacent to the catheter entry site and four at a distance, including two cases of cerebral hemorrhage, one of which was fatal.

CONCLUSIONS

Transthrombus bolus delivery of tissue plasminogen activator followed by a low-dose infusion shortens lysis time, but this technique appears to be associated with an increased risk of serious hemorrhage.

Use of Blount's epiphyseal staples to control massive iliac venous haemorrhage

Significant injuries to major veins are life-threatening events and may lead to patient exsanguination. Treatment usually consists of direct suture repair. A case in which a serious iliac venous haemorrhage was not able to be controlled with the usual surgical procedures is reported. A desperate attempt to achieve haemostasis using orthopaedic staples was successful. The simplicity of this technique makes it a useful addition to the surgeon's armamentarium when dealing with life-threatening venous haemorrhage.

Salmonella infection of a Dacron aortic bifurcation graft

We report a case of primary salmonella infection of a dacron aortofemoral bypass graft. Local graft excision with extra-anatomic bypass resulted in a successful outcome. Salmonella, whilst the commonest cause of infected abdominal aortic aneurysms, is currently a rare cause of prosthetic graft infection. However, given the increasing prevalence of salmonellosis in the community, we believe this situation will change and surgeons should be alert to this new and dangerous addition to the list of graft pathogens.

Aortic aneurysmal disease. A generalized dilating diathesis

The association of dilated peripheral arteries with aortic aneurysmal disease has previously been suspected, but is not well documented. To test this association, the diameters of the common femoral, popliteal, brachial, common carotid, internal carotid, and external carotid arteries were measured with a color-flow duplex scan in 30 control subjects and 36 patients with aortic aneurysm matched for age, sex, smoking habits, and hypertension. Mean peripheral artery diameter was significantly greater in patients with aortic aneurysm than in controls at all measurement sites. Peripheral artery dilatation was identified at sites that are seldom, if ever, involved in atherosclerosis. These findings lend support to the view that there is a generalized dilating diathesis in aortic aneurysmal disease that may be unrelated to atherosclerosis.

Perioperative experience: an essential component for nursing education

1. Many of today's nursing curricula have limited or no exposure in perioperative nursing. This deficit probably has contributed to the current crisis level in the shortage of nurses occurring in this area. 2. As a recruitment tool and orientation package, the clinical practicum and perioperative elective are a cost-effective means of teaching, increase the self-esteem of the graduates, and provide long-term problem solving experiences. 3. In addition to applying accrued theory to a clinical setting for an extended period, students are allowed to experience an area of nursing without a formal commitment to an agency.

Ureteral obstruction following aortobifemoral bypass: management by endoscopic balloon dilation

A 71-year-old man presented with left hydronephrosis 1 year after aortofemoral bypass. Hydronephrosis was due to extrinsic compression of the ureter between the graft anteriorly and the native iliac artery. Treatment by endoscopic transluminal balloon dilation resulted in complete resolution of the hydronephrosis.

Acute visceral ischemia secondary to aortic graft occlusion

This report describes a case of acute visceral ischemia precipitated by aortic graft occlusion. The importance of recognizing and treating visceral artery lesions at the time of aortic reconstruction is emphasized.

Supraceliac clamping: an underused alternative in aortic surgery

In the majority of patients undergoing abdominal aortic surgery, proximal clamping can be readily achieved below the renal vessels. In some situations however, this may be difficult, impossible or ill advised, and an alternative method of control must be sought. We describe the technique and report our personal experience with supraceliac clamping, a maneuver which merits more widespread use in emergency and difficult infrarenal aortic surgery.

Adventitial cystic disease of the popliteal artery

A case of adventitial cystic disease of the popliteal artery is described and the subject reviewed. Now that radiologists will often follow arteriography with angioplasty or thrombolytic therapy, it is particularly important that this condition is recognised.

Some aspects of ultrasound in the diagnosis and assessment of aortoiliac disease

The presence and severity of aortoiliac atherosclerosis were assessed in 60 normal limbs and 54 limbs with peripheral vascular disease by means of arteriography, clinical examination and ultrasound analysis. The latter involved common femoral sonogram analysis with particular measurement of the pulsatility index, a study of transit time ratios and measurement of the half recovery time during reactive hyperemia. The transit time data were of limited value and only capable of diagnosing aortoiliac disease when complete occlusion was present. The pulsatility index and half recovery time were more sensitive indicators of aortoiliac disease, and both were superior to clinical examination alone. Their values became increasingly abnormal with increasing severity of disease, and both reverted to normal after successful aortoiliac surgery. When it was possible to directly inspect the aortoiliac segment at operation, the half recovery time accurately predicted the presence or absence of aortoiliac disease in every case, and its use as a reliable screen for aortoiliac disease is particularly recommended.

Infection complicating aortoiliac surgery

25 cases of sepsis complicating aorto-iliac surgery have been encountered in the period 1970 to 1976 (8 cases occured in our own unit and 17 were received from elsewhere). There were 10 instances of infection following thromboendarterectomy and all 10 were treated successfully. Among the 19 patients with infected prostheses (14 primary, 5 secondary) there were 5 deaths(1 myocardial infarct, 2 septicaemia, 2 aortic haemorrhages) and 3 amputations. The treatment of choice for infected thromboendarterectomy cases is iliac exclusion coupled with either an obturator by-pass or a femoro-femoral vein graft using the perineal route. An infected prosthesis should be removed and circulation restored by means of an axillofemoral-bypass, or a femoro-femoral vein graft or a combination of the two. Occasionally an infected aorto-femoral prosthesis can be treated by removal of one limb only followed by obturator or axillo-femoral by-pass. The prophylactic value of omentopexy in aortoiliac surgery is emphasised.

The role of the profunda femoris in aorto-iliac surgery

The results of aorto-iliac surgery in 90 ischaemic limbs (68 patients) have been reviewed. The mean follow-up period was 18 months (rang 6 monts to 3.5 years). In 48 limbs the disease was confined to the aorto-iliac segment (group 1), while in 42 limbs severe occlusive changes were present in both the aorto-iliac and superficial femoral segments (group 2).

In group intermittent claudication was obolised or substanitally improved in 86 per cent. Rest pain was relieved in all cases. Lumbar sympathectomy was with out obvious additional benefit in either group. Pedal pules were restored in all except 3 limbs. A highly significant (P &lt;0.001) increase in the ankle systolic pressure (ASP) index occurred after surgery and normal values were restored both in claudicants and in those with rest pain. This response was maintained through out the follow-up period.

Claudication was effectively relived in 38 per cent of cases in group 2 following aortoprofunda reconstruction. Rest pain was abolished in 83 per cent of cases, the remainder requrining a major amputation. Lumbar sympathectomy failed to produce any additional benefit among either claudicants or those with rest pain. Pedal pulses were restored in only 2 limbs. Among claudicants the ASP index was uncharged, and although a significatn (P &lt;0.001) increase occurred in the rest pain group, the index remained within the ischaemic range. There was little variation in the value of the ASP index throughout the follow-up period in either group. The difference between the ASP response to surgery in patients with aorto-iliac disese alone and those with dual occlusion was highly significant (P &lt;0.001).

The present results suggest that among claudicants revascularization of the profunda alone may be followed by a limited clinical and hoemodynamic response. However, as a limb salvage procedure, aortoprofunda reconstruction can be recommended with confidence. When both the superficial and deep femoral vessels are patent, on excellent response is to be expected after aorto-iliac surgery in claudicants and patients with rest pain alike.

Platelet aggregation in patients with peripheral vascular disease

Platelet aggregation has been studied in 28 control subjects and 46 patients with peripheral vascular disease. The platelets from the patients with peripheral vascular disease were significantly more sensitive to the aggregating effects of adenosine diphosphate and adrenaline than those from the control group (P less than 0.001). In addition, spontaneous platelet aggregation was observed in vitro in several of the vascular patients; this response was not apparent in the control group. Increased platelet aggregation could add to the vascular impairment in the unoperated subject and might also play a part in premature graft failure. Platelet function studies should perhaps be included as a routine in the assessment of patients with peripheral vascular disease.