Long-term expression of murine activated factor VII is safe, but elevated levels cause premature mortality

Intravenous infusion of recombinant human activated Factor VII (FVIIa) has been used for over a decade in the successful management of bleeding episodes in patients with inhibitory antibodies to Factor VIII or Factor IX. Previously, we showed that expression of murine FVIIa (mFVIIa) from an adeno-associated viral (AAV) vector corrected abnormal hemostatic parameters in hemophilia B mice. To pursue this as a therapeutic approach, we sought to define safe and effective levels of FVIIa for continuous expression. In mice transgenic for mFVIIa or injected with AAV-mFVIIa, we analyzed survival, expression levels, in vitro and in vivo coagulation tests, and histopathology for up to 16 months after birth/mFVIIa expression. We found that continuous expression of mFVIIa at levels at or below 1.5 microg/ml was safe, effective, and compatible with a normal lifespan. However, expression levels of 2 microg/ml or higher were associated with thrombosis and early mortality, with pathologic findings in the heart and lungs that were rescued in a low-factor X (low-FX) mouse background, suggesting a FX-mediated effect. The findings from these mouse models of continuous FVIIa expression have implications for the development of a safe gene transfer approach for hemophilia and are consistent with the possibility of thromboembolic risk of continuously elevated FVIIa levels.

Transition to injection drug use among street youth--a qualitative analysis

OBJECTIVES

To examine social contexts and processes influencing transition to drug injection among street youth.

METHODS

42 street youth participated in in-depth interviews. A typology of experiences was built founded on youth's street life and drug use trajectories. The transition to drug injection was examined through these experiences.

RESULTS

We identified five types of mutually exclusive experiences. The "downtowner's" experience is characterised by early street life and drug consumption trajectories, and a strong identification with the downtown milieu. These youth progress from one drug to another and, in a milieu where drug injection is omnipresent, this escalation culminates in transition to injection. The "tripper" street life and substance use trajectories begin later and are less intense. Most "tripper" youth are already chronic hallucinogens users when they arrive in downtown Montréal. Although they judge "junkies" severely, they show some ambivalence towards injection. The "on the go" experience is characterised by trajectories of drug use and street life that are intermingled, leading to a loss of control. These youth, who often have serious delinquent behaviours, come to downtown Montréal to party and consume drugs, mostly stimulants. Their drug use pattern and network make them at high risk of starting cocaine injection. The "hard-luck's" experience is characterised by a lack of identification with the downtown milieu. These youth who use drugs recreationally, end up in the streets accidentally, often because of unemployment. The "alcoholic' experience is related to alcohol misuse. These youth usually end up in the streets due to this dependence. Their street involvement is mostly an experience of solitude. The risk of transitioning to injection for both these types is low.

CONCLUSIONS

Some combinations of street life and drug use trajectories seem to contribute to injection among street youth. Some important factors interact and increase the risk of street youth transitioning to injection: poor personal assets; early rupture with primary social institutions; social integration into subcultures where both street life and "drug trips" are fashionable, drug preferences and the local drug market.

Trends in injection drug use behaviors over 10 years among street youth

OBJECTIVES

To determine the temporal trends of initiation into injection drug use, current injection, and recent receptive sharing of injection paraphernalia among street youth.

DESIGN

Data from two cohort studies conducted between 1995 and 2005 were combined.

METHODS

Recruitment was done on an ongoing basis. Interviews were performed semi-annually. Overall and annual drug injection incidence rates were calculated with the person-time method. Poisson regression was used to assess the predictive power of calendar year on incidence rate. Generalized estimating equations (GEE) were used to assess linear trends in current injection among street youth and in recent receptive sharing of syringe and other injection paraphernalia among current injection drug users.

RESULTS

By 31 March 2005, 1633 subjects had completed 8875 questionnaires. Most subjects were born in Canada (94%), their mean age at entry was 20 years, 68% were boys and almost half (44%) had injected drugs before recruitment. Among 778 never injectors at entry, 130 subjects initiated injection in 1898 person-years of follow-up (incidence rate: 6.8 per 100 person-years). When controlling for age, calendar year was not a significant predictor of incidence rate. Prevalence of current injection was stable (around 30%). Odds of both sharing behaviors decreased by approximately 10% per year.

CONCLUSIONS

In addition to injection paraphernalia sharing reduction efforts, interventions aimed at preventing initiation into injection drug use among high-risk youth are needed.

High hepatitis C virus prevalence and incidence among Canadian intravenous drug users

We used data and leftover samples collected through the SurvUDI network to describe the epidemiology of hepatitis C virus (HCV) infection among injection drug users (IDUs) in Eastern Central Canada. Among the 1380 selected IDUs, having participated twice or more between 1997 and 2003, the overall HCV prevalence rate was 60.4% (95% confidence interval [CI]: 57.7-63.0%). Among the 543 initially uninfected participants, the HCV incidence rate was 27.1 per 100 person-years (95% CI: 23.4-30.9 per 100 person-years). Independent predictors of seroconversion, identified among 359 participants, were age, injecting for a year or less, injecting with a syringe previously used by someone else, injecting most often cocaine, engaging in prostitution, and being recruited in a major urban centre. The HCV epidemic severely affects IDUs in this area. Actions to prevent HCV transmission, such as distribution of sterile injection equipment, have to be reinforced. Special efforts have to be targeted towards starting IDUs.

The health of street youth: a Canadian perspective

OBJECTIVE

To review epidemiologic studies of the health of street youth in industrialized countries, with a special focus on Canadian youth.

METHODS

We identified 52 peer-reviewed studies from searches of the MEDLINE database and bibliographies of published papers, for data on blood-borne and sexually transmitted infections, mental health problems, pregnancy, violence and mortality.

RESULTS

Rates of hepatitis B, hepatitis C, and HIV infection are much higher among street youth than among their non-street peers. Likewise, the prevalence of all mental health problems assessed in street youth is greater than that in non-street youth. Pregnancy is more frequent among street than household youth. Street youth also experience high levels of violence: a large proportion report physical abuse or assault. Finally, mortality is about 11 times the expected rate based on age and sex and is mainly caused by suicide and drug overdose.

CONCLUSION

Current research results are useful to orient public health interventions for street youth, but further epidemiologic research is needed. The need for Canadian data is particularly acute in specific areas including mental health, violence, pregnancy, and sexually transmitted infections such as, for example, herpes infection and syphilis.

[Pulmonary bilharziosis due to Schistosoma haematobium: pitfalls of species diagnosis. A case report from Libreville, Gabon]

The purpose of this report is to describe a case of pulmonary schistosomiasis treated at la Fondation Jeanne Ebori in Libreville, Gabon. This case is exceptional due to the rarity of the disease and the schistosomiasis agent involved. The patient was a 47-year-old woman who presented with recurrent right-sided pneumonia 6 months after initial hospitalization and nonspecific antimicrobial therapy. Her general status was altered by hyperthermia, right chest pain, and repetitive bouts of hemoptysia. Because etiological diagnosis could not be achieved and clinical condition was deteriorating, the decision was taken to perform exploratory thoracotomy. Based on operative findings, medial and lower lobectomy was performed. Histological examination demonstrated granulomatous inflammatory lesions due to bilharziosis. Infection was attributed to Schistosoma haematobium that is the most common agent in pulmonary localizations. However Ziehl coloration raised the possibility of involvement of Schistosoma intercalatum that has never been observed in the lung and of a hybrid species. Natural hybridization between S. haematobium and S. intercalatum and the presence of active transmission of the Schistosoma hybrid has been suspected in Gabon.

HIV risk profile of male street youth involved in survival sex

OBJECTIVES

To compare HIV risk factors of male street youth involved in survival sex with those of their never involved peers and to describe the sexual activities of the involved youths.

METHODS

From 2001 to 2003, street youth aged 14-23 years were recruited from street youth agencies in Montreal, Canada. Information was collected on sociodemographic characteristics, substance use, and sexual behaviours. Involvement in survival sex was defined as having ever exchanged sex for money, gifts, drugs, shelter, or other needs. Logistic regression was used to identify HIV risk factors associated with involvement in survival sex.

RESULTS

Among the 542 male participants recruited, 27.7% reported involvement in survival sex. HIV risk factors independently associated with such involvement were injection drug using partners (modulated by length of homelessness), unprotected oral sex with male partners, steroid injection, history of sexual abuse, and drug injection. Among involved youths, 32.0% had only female clients, 41.3% only male clients, and 26.7% had clients of both sexes. Unprotected sexual activities were common with clients. However, even more risks were taken with non-commercial sexual partners.

CONCLUSIONS

Male street youth involved in survival sex are at higher risk for HIV than their non-involved peers not only because of their unprotected commercial sexual activities. They have multiple other HIV risks related to non-commercial sexual activities, drug injection, and sexual abuse. All these risks need to be addressed when providing sexual health interventions for this population.

Predictors of initiation into prostitution among female street youths

Prostitution among female street youths represents an important risk factor for several health problems. Little is known about the incidence and determinants of prostitution in this vulnerable population, and no data have been previously reported based on a longitudinal follow-up study. The objective of this study was to determine predictors of initiation into prostitution among female street youths. Female youths aged 14 to 25 years were enrolled in the Montreal Street Youth Cohort. They completed a baseline and at least one follow-up questionnaire between January 1995 and March 2000. Girls who reported never having engaged in prostitution at baseline were followed prospectively to estimate the incidence and predictors of prostitution. Of the 330 female street youths enrolled as of September 2000 in the cohort, 148 reported no history of involvement in prostitution at baseline and completed at least one follow-up questionnaire. Of these 148 girls, 33 became involved in prostitution over the course of the study (mean follow-up 2.4 years), resulting in an incidence rate of 11.1/100 person-years. Multivariate Cox regression analysis revealed having a female sex partner (adjusted hazard ratio [AHR] 3.8; 95% confidence interval [CI] 1.6-9.1) was an independent predictor of initiation into prostitution after controlling for having been on the street at age 15 years or younger (AHR 1.8, 95% CI 0.9-3.8), using acid or phencyclidine (PCP; AHR 2.0, 95% CI 0.9-4.6), using heroin (AHR 1.9, 95% CI 0.7-5.5), the use of drugs greater than twice per week (AHR 1.9, 95% CI 0.9-4.2), and injection drug use (AHR 0.8, 95% CI 0.3-2.4). The incidence of prostitution in female street youths was elevated. Having a female sex partner was a strong predictor of initiating involvement in prostitution.

Characteristics of adolescent street youth with a history of pregnancy

This study examines characteristics of adolescent street youth with histories of pregnancy and documents important factors that merit consideration when providing global sexual health care.

STUDY OBJECTIVE

To determine social and behavioral factors associated with a history of pregnancy among adolescent street youth.

DESIGN, SETTING, PARTICIPANTS

In a prospective cohort study, female adolescent street youth (14-19 years) ever pregnant (AEP) were compared with adolescents never pregnant (ANP) using data from baseline questionnaires.

RESULTS

Among the 225 participants, 41.8% were ever pregnant. Both groups were similar with respect to age (mean 17.8 years) and other socio-economic characteristics. However, AEP were more likely to have been kicked out of home (62.8% vs. 47.3%, P=0.022) and to have run away (78.7% vs. 64.9%, P=0.025) and were homeless younger (mean age: 13.9 vs. 14.7 years, P=0.011) and since a longer period (mean: 4.0 vs. 3.0 years, P=0.001). Both groups had problematic alcohol and drug use: 31.3% had a CAGE score >2; 72.2% had a DAST score >6. Almost half (44.0%) had ever injected drugs and AEP were younger at initiation into drug injection (15.2 years vs. 16.0 years, P=0.049). More AEP had experienced intra-familial or extra-familial sexual abuse (71.3% vs. 56.5%, P=0.024), and had had more than one abuser (71.6% vs. 50.0%, P=0.009). Among those abused by family members, abuse occurred at an earlier age for AEP (mean age: 7.4 vs. 8.9 years, P=0.090) and more AEP reported severe abuse: vaginal penetration (62.2% vs. 26.7%, P=0.004) and anal penetration (29.7% vs. 3.3%, P=0.005).

CONCLUSIONS

Histories of severe sexual abuse and early injection drug use are extremely frequent in ever pregnant street adolescents. These factors need to be addressed when planning global health care and sexual health education.

Mortality in a cohort of street youth in Montreal

CONTEXT

Many studies have shown a high prevalence of sexually transmitted diseases, human immunodeficiency virus (HIV) infection, viral hepatitis, drug dependence, and mental health problems among street youth. However, data on mortality among these youth are sparse.

OBJECTIVES

To estimate mortality rate among street youth in Montreal and to identify causes of death and factors increasing the risk of death.

DESIGN, SETTING, AND POPULATION

From January 1995 to September 2000, 1013 street youth 14 to 25 years of age were recruited in a prospective cohort with semi-annual follow-ups. Original study objectives were to determine the incidence and risk factors for HIV infection in that population; however, several participants died during the first months of follow-up, prompting investigators to add mortality to the study objectives. Mortality data were obtained from the coroner's office and the Institut de la Statistique du Québec.

MAIN OUTCOME MEASURES

Mortality rate among participants and factors increasing the risk of death.

RESULTS

Twenty-six youth died during follow-up for a mortality rate of 921 per 100 000 person-years (95% confidence interval [CI], 602-1350); this represented a standardized mortality ratio of 11.4. The observed causes of death were as follows: suicide (13), overdose (8), unintentional injury (2), fulminant hepatitis A (1), heart disease (1); 1 was unidentified. In multivariate Cox regression analyses, HIV infection (adjusted hazard ratio [AHR] = 5.6; 95% CI, 1.9-16.8), daily alcohol use in the last month (AHR = 3.2; 95% CI, 1.3-7.7), homelessness in the last 6 months (AHR = 3.0; 95% CI, 1.1-7.6), drug injection in the last 6 months (AHR = 2.7; 95% CI, 1.2-6.2), and male sex (AHR = 2.6; 95% CI, 0.9-7.7) were identified as independent predictors of mortality.

CONCLUSIONS

Current heavy substance use and homelessness were factors associated with death among street youth. HIV infection was also identified as an important predictor of mortality; however, its role remains to be clarified. These findings should be taken into account when developing interventions to prevent mortality among street youth.

Rett syndrome as a minicolumnopathy

OBJECTIVE

Rett syndrome is a progressive neurological disorder affecting primarily females. It is characterized by the early regression of acquired language, cognitive functions, social skills, and purposeful hand function. Patients with Rett syndrome are often misdiagnosed as autistic. Recent reports of minicolumnar abnormalities in the brains of autistic and Asperger's syndrome prompted us to search for similar pathology in Rett syndrome.

MATERIAL

The patient population consisted of 5 Rett syndrome patients (mean age = 14.4 +/- 4.0 years) and 17 controls (mean age = 14.6 +/- 9.5 years). Tissue was celloidin embedded, sectioned at 35 um and Nissl stained. Images (100x) were taken from Brodmann's areas 9, 21, and 22 from layer III of the left hemisphere.

METHOD

Columnar width measurements for these images were obtained with computerized image analysis using previously published algorithms. Each area was analyzed separately with univariate ANOVA, including diagnosis as a fixed factor and age (linear and quadratic terms), and sex as covariates.

RESULTS

Diagnosis dependent effects were statistically significant only in area 21 (p = 0.009) even when taking into account a Bonferroni correction for the multiple comparisons.

CONCLUSION

Both the regional nature of the changes as well as differences in mean cell spacing differentiates the abnormal minicolumnar morphometry of Rett syndrome from that of autism.

HIV incidence among street youth in Montreal, Canada

OBJECTIVES

To estimate HIV incidence and identify predictors of seroconversion among Montreal street youth.

METHODS

From 1995 to 2000, street youth aged 14-25 years were recruited in a prospective cohort study. Interviews were conducted semiannually and included anti-HIV antibody testing. Among subjects who tested HIV negative at study entry and were interviewed at least twice, predictors of HIV seroconversion were identified using Cox regression. Variables considered as potential predictors were age, sex, injection drug use, being a male reporting male sexual partners, and survival sex.

RESULTS

Overall, 1013 youth were recruited in the study. HIV prevalence at study entry was 1.4% [95% confidence interval (CI) 0.8-2.4] and was stable over the 6 recruitment years. Among the 863 subjects selected for the incidence analysis, 66.7% were boys, 47.2% had ever injected drugs at study entry, and 25.7% had ever engaged in survival sex. The selected participants cumulated 2327 person-years of follow-up and 16 HIV seroconversions were observed, for an incidence rate of 0.69 per 100 person-years (95% CI 0.39-1.11). In univariate analysis, injection drug use [hazard ratio (HR), 7.0] and involvement in survival sex (HR, 4.0) were associated with HIV incidence. In the multivariate analysis, only injection drug use was retained.

CONCLUSIONS

Among Montreal street youth, injection drug use was the strongest predictor of HIV seroconversion. Prevention of initiation into injection drug use must become a public health priority.

Drug injection among street youths in Montreal: predictors of initiation

In North America, street youths are generally considered at very high risk of injection drug use. To estimate the incidence rate of injection drug use in this population and to identify predictors of injection drug use, we conducted the present analysis. Among participants to a cohort study initiated in January 1995, we selected subjects who had never injected at study entry and had completed at least one follow-up questionnaire. Predictors of initiation were identified using Cox proportional hazard regression models. Among the 415 never injectors (mean age at entry 19.5 years), 74 had initiated injection by January 2000 (incidence rate 8.2 per 100 person-years). Independent predictors of initiation were recent episode of homelessness; age younger than 18 years; being tattooed; recently using hallucinogens, heroin, and cocaine/crack/freebase; having a friend who injects drugs; and having ever experienced extrafamilial sexual abuse. This study showed that injection drug use is frequent among street youths, but prevention appears possible.

Drug injection among street youth: the first time

AIMS

To describe the circumstances of the first drug injection among street youth.

DESIGN

A cohort study conducted in 1995-2000.

PARTICIPANTS

Subjects aged 14-25 years old were recruited in all major Montreal organizations offering free services to street youth.

MEASUREMENT

Subjects who reported having ever injected drugs completed questions on the circumstances of their first injection (calendar time, location, type of relationship with the initiator, presence of others, drug first injected, source of needle and use of clean needle and other injection materials). Questions on characteristics of the initiator and prior use of the first injected drug were added during the course of the study.

FINDINGS

Of 980 participants, 530 (54%) had ever injected drugs. Questionnaires were completed by 505 subjects, including 77 who also answered the additional questions. The mean age at first injection was 17.7 years. First injection occurred mainly in public places (41%). It was performed by a close friend (41%), the youth himself/herself (27%), an acquaintance (15%), a lover (10%) or another person (7%). Overall, 84% of youth first injected with a clean needle; only 62% used clean drug preparation equipment. The first drug injected was generally cocaine (47%) or heroin (41%). Two-thirds (53/77) had used the drug of first injection previously; however, the majority was not dependent upon it.

CONCLUSIONS

Most street youth used clean needles at first injection, but use of other clean injection materials was less frequent. Factors other than dependence appear to play a significant role in initiation into injection.

Risk behaviours and prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae genital infections among Montreal street youth

We estimated the prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae genital tract infections among 302 Montreal street youth (223 boys) and identified associated risk factors. Study participants, 14-25 years old (average 20.9 years), meeting specific criteria for homelessness, were recruited in street youth agencies. Participation included a structured interview and provision of a urine specimen. Among sexually active youth, (n = 300) 30.0% had more than five heterosexual partners and 13.0% had at least one homosexual partner (last year), 10.7% had received money in exchange for sex (last six months) and 47.0% reported sexual relations resulting in pregnancy (lifetime). Among all youths, 82.1% had used at least one type of illicit drug, and 30.1% injected drugs at least once (last six months). The prevalence of C. trachomatis infection was 6.6% (95% CI 4.1-10.0%). Prevalence did not vary significantly by sex, age or any other variable, except history of pregnancy (10.4% among youth with history of pregnancy vs 3.6% among others, P = 0.02). No cases of N. gonorrhoeae infection were found.

Quantitative comparison of radial cell columns in children with Down's syndrome and controls

No one has examined the configuration of the minicolumns in Down's syndrome (DS) brains even though these are a basic functional unit of the cortex. In the present study, the authors used computerized imaging to examine minicolumns in the posterior superior temporal gyrus in both the brains of patients with DS and normal controls. They compared the brains of children aged 4 and 6 years with those of adults for both people with DS and the normal population. Columns in the brains of two DS children aged 4 and 6 years were almost the same size as those of the adults with DS. The neuropil space in the periphery of the columns was also considerably wider. In contrast, minicolumns in aged-matched control children were smaller, both relatively and absolutely, when compared to the mean size of adult columns. The size of the minicolumns in the normal children apparently corresponded to the overall brain size, whereas the large columns in children with DS appeared to be independent of brain size, at least in area Tpt. This seems to reflect a rapid ageing process that is striking when compared to normal controls. Columns in adults with DS were large and less cell dense, while brain volumes were significantly smaller than in controls. This combination suggests reduced neuronal complexity based on a decrease in processing units, which supports previous findings of decreased cell numbers and synaptic diminution in DS brains.

Seroprevalence and risk factors for hepatitis A among Montreal street youth

OBJECTIVE

To estimate the prevalence of hepatitis A virus (HAV) antibodies among Montreal street youth.

METHOD

Anti-HAV antibody testing was performed on blood samples from a hepatitis B and C study conducted among street youth in 1995-96.

RESULTS

Among the 427 youth aged 14 to 25 years, prevalence of HAV antibodies was 4.7% (95% confidence interval [CI]: 2.9%-7.2%). A multivariate logistic regression analysis showed that birth in a country with a high anti-HAV prevalence (Adjusted odds ratio [AOR]: 200.7; 95% CI: 38.1-1058.4), having had sexual partner(s) with history of unspecified hepatitis (AOR: 13.8; 95% CI: 4.2-45.2), and insertive anal penetration (AOR: 5.1; 95% CI: 1.6-16.7) were independently associated with infection.

CONCLUSION

Based on the relatively low HAV prevalence, the high prevalence of risk factors for infection, and the substantial hepatitis B and C prevalence, vaccination against hepatitis A is now actively promoted among Montreal street youth.

Risk factors for hepatitis C virus infection among street youths

BACKGROUND

The relative contributions to risk of hepatitis C virus (HCV) infection resulting from unsafe sexual behaviours and exposures to blood (e.g., tattooing, body piercing and injection drug use) among youths at risk are not well known. We interviewed street youths about risk factors for HCV infection and documented their HCV antibody status.

METHODS

From December 1995 to September 1996 we recruited 437 youths aged 14 to 25 years who met specific criteria for itinerancy. Data on sociodemographic characteristics and lifetime risk factors were obtained during a structured interview, and a venous blood sample was taken for HCV antibody testing.

RESULTS

Many of the subjects reported behaviours that put them at risk for blood-borne diseases: 45.8% had injected drugs, 56.5% had at least 1 tattoo, and 78.3% had body piercing. The overall prevalence of HCV infection was 12.6% (95% confidence interval [CI] 9.7%-15.9%). In a multivariate logistic regression analysis, injecting drugs (adjusted odds ratio [OR] 28.4 [95% CI 6.6-121.4]), being over 18 years of age (adjusted OR 3.3 [95% CI 1.6-7.0]) and using crack cocaine (adjusted OR 2.3 [95% CI 1.0-5.3]) were independent risk factors for HCV infection. Having more than 1 tattoo (adjusted OR 1.8 [95% CI 0.95-3.6]) was marginally associated with HCV infection, and body piercing was not.

INTERPRETATION

Drug injection was the factor most strongly associated with HCV infection among street youths. Given that injection drug users are the driving force of the HCV infection epidemic in Canada, increased intervention efforts to prevent initiation of drug injection are urgently needed to curb the epidemic.

Electrochemical synthesis of antimony nanowires and analysis of diffusion layers

Synthesis of an array of antimony nanowires was performed by electrodeposition within a porous polycarbonate membrane. The sizes of pores range from 30 to 400 nm in diameter and their densities vary from 2 x 10(+6) to 2 x 10(+9) pores/cm2. To obtain optimal conditions for nanowire preparation, plating behavior was investigated by a potentiostatic method with two types (continued or pulsed) of polarization. The chronoamperometry revealed that responses depend on the type of polarization and on the pore density of the membrane. With high-density membranes, the diffusion layers of each individual pore immediately overlap when they reach the external part of the membrane. This leads to an abrupt decrease of current intensity. This phenomenon is not observed with low-density membranes because of the greater distance between pores. This mechanism, which was investigated in antimony nanowire plating, is applicable to electrodeposition of other types of materials.

New method of cardiac output measurement using ultrasound velocity dilution in rats

The aim of this study was to validate a new technique for the measurement of cardiac output (CO) based on ultrasound and dilution (COUD) in anesthetized rats. A transit time ultrasound (TTU) probe was placed around the rat carotid artery, and ultrasound velocity dilution curves were generated on intravenous injections of saline. CO by COUD were calculated from the dilution curves for normal and portal hypertensive rats in which CO was known to be increased. COUD was compared with the radiolabeled microsphere method and with direct aortic TTU flowmetry for baseline CO and drug-induced CO variations. CO in direct aortic TTU flowmetry was the ascending aorta blood flow measured directly by TTU probe (normal use of TTU flowmetry). The reproducibility of COUD within the same animal was also determined under baseline conditions. COUD detected the known CO increase in portal hypertensive rats compared with normal rats. CO values by COUD were correlated with those provided by microsphere technique or direct aortic TTU flowmetry (adjusted r = 0.76, P < 10(-4) and r = 0.79, P < 0.05, respectively). Baseline CO values and terlipressin-induced CO variations were detected by COUD and the other techniques. Intra- and interobserver agreements for COUD were excellent (intraclass r = 0.99 and 0.98, respectively). COUD was reproducible at least 10 times in 20 min. COUD is an accurate and reproducible method providing low-cost, repetitive CO measurements without open-chest surgery. It can be used in rats as an alternative to the microsphere method and to direct aortic flowmetry.

Morphological differences between minicolumns in human and nonhuman primate cortex

Our study performed a quantitative investigation of minicolumns in the planum temporale (PT) of human, chimpanzee, and rhesus monkey brains. This analysis distinguished minicolumns in the human cortex from those of the other nonhuman primates. Human cell columns are larger, contain more neuropil space, and pack more cells into the core area of the column than those of the other primates tested. Because the minicolumn is a basic anatomical and functional unit of the cortex, this strong evidence showed reorganization in this area of the human brain. The relationship between the minicolumn and cortical volume is also discussed.