The associations of total and differential white blood cell counts with obesity, hypertension, dyslipidemia and glucose intolerance in a Korean population

Although many studies have reported an association between total white blood cell count and metabolic syndrome, relatively few reports are available on the association between differential white blood cell counts and metabolic syndrome. The medical records of 15,654 subjects (age, median 46, range 14-90 yr; 8,380 men and 7,274 women) who visited the Center for Health Promotion were investigated. It was found that as total white blood cell (WBC) and differential WBC counts increased the frequencies of diabetes, hypertension, obesity, dyslipidemia, and metabolic syndrome also increased. Moreover, these significant relationships persisted after adjusting for age, gender, smoking, alcohol intake, educational background, and household income. The odds ratios (95% CI) for metabolic syndrome was 2.64 (2.30- 3.04) in the highest quartile of total WBC count, with corresponding figures of 2.14 (1.88-2.44) for neutrophils, 2.32 (2.03-2.64) for lymphocytes, 1.56 (1.37-1.78) for monocytes, 1.36 (1.20-1.54) for basophils, and 1.82 (1.59-2.08) for eosinophils versus the lowest quartiles of the appropriate total and differential counts, respectively, after adjusting for the variables mentioned above. These independent associations were also observed by subgroup analyses according to the smoking status. Our data suggest that even within normal ranges, total WBC count and the differential WBC counts are associated with the presence of metabolic syndrome.

Association between heart rate recovery after exercise testing and plasminogen activator inhibitor 1, tissue plasminogen activator, and fibrinogen in apparently healthy men

OBJECTIVE

Delayed heart rate recovery (HRR) following exercise testing, an indicator of decreased autonomic nervous system activity, is associated with an increased risk of cardiovascular events. Because autonomic nervous system function may be associated with fibrinolytic factors, we tested the hypothesis that delayed HRR is associated with elevated fibrinolytic factors.

METHODS

In 547 (mean age 49.4+/-6.9 years) healthy men who underwent exercise treadmill testing and fasting blood analysis for fibrinolytic factors, we calculated HRR as the difference between maximum heart rate during the test and heart rate 1 min after cessation of exercise.

RESULTS

HRR was inversely correlated with plasminogen activator inhibitor 1 (PAI-1) activity (r=-0.23, p<0.001), tissue plasminogen activator (t-PA) antigen (r=-0.19, p<0.001), and fibrinogen (r=-0.11, p<0.05). Men in the lowest quartile of HRR had significantly higher PAI-1, t-PA, and fibrinogen than men in the highest quartile of HRR (all p trend <0.001). HRR was independently associated with PAI-1 (beta=-0.12, p<0.01) and fibrinogen (beta=-0.09, p=0.04) but not t-PA (beta=-0.06, p=0.29) in a multiple regression analysis.

CONCLUSIONS

These results suggest that delayed HRR after exercise testing is associated with elevated fibrinolytic factors in cross-section. The presence of other CHD risk factors does not explain this association, but further research is needed to identify the direction of the association.

Pharmacokinetic interaction between DA-8159, a new erectogenic, and metformin in rats: competitive inhibition of metabolism via hepatic CYP3A1/2

BACKGROUND AND PURPOSE

Erectile dysfunction is highly prevalent in diabetic patients and PDE V inhibitors are effective and safe for the treatment of erectile dysfunction in men with diabetes. Therefore, in this study we investigated whether a pharmacokinetic interaction occurs between DA-8159 and metformin, as both drugs are metabolized via hepatic CYP3A1/2 in rats.

EXPERIMENTAL APPROACH

DA-8159 (30 mg kg(-1)) and metformin (100 mg kg(-1)), both separately and together, were administered to rats either intravenously or orally. The V (max), K (m), CL(int), apparent inhibition constants (K (i)), [I]/K (i) and concentrations of each drug in the liver and intestine were then measured.

KEY RESULTS

After i.v. administration of both drugs simultaneously, the AUC of DA-8159 and metformin was significantly greater (21.2 and 33.9% increase for DA-8159 and metformin, respectively) than that of each drug alone. After p.o. administration of the drugs, the AUC of metformin was also significantly greater (20.7% increase) in the presence of DA-8159 than in its absence. However, the AUC of DA-8159 was similar in the absence and presence of metformin.

CONCLUSIONS AND IMPLICATIONS

The significantly greater AUC of metformin and DA-8159 after i.v. administration of both drugs and of metformin after p.o. administration of both drugs is probably due to competitive inhibition for the metabolism of these drugs via hepatic CYP3A1/2. However, the similar AUCs of DA-8159 in the absence and presence of metformin, after p.o. administration, indicates that the dose of metformin used was insufficient to inhibit the hepatic and intestinal metabolism of DA-8159.

Slow heart rate recovery after exercise is associated with carotid atherosclerosis

OBJECTIVE

Slow heart rate recovery (HRR) after exercise is an estimate of impaired parasympathetic tone and predictor of all-cause and cardiovascular mortality. Carotid atherosclerosis is associated with high risk of developing coronary heart disease (CHD) and stroke. We tested the hypothesis that slow HRR is associated with carotid atherosclerosis in a cross-sectional study of 12,712 middle-aged men (age 49.1+/-8.9 years).

METHODS

Carotid atherosclerosis was measured using B-mode ultrasonography and defined as stenosis >25% and/or intima-media thickness >1.2mm. HRR was calculated as the difference between peak heart rate during a graded exercise treadmill test and heart rate 2 min after cessation of exercise.

RESULTS

The prevalence of carotid atherosclerosis was 8.4%. The prevalence of atherosclerosis was significantly higher among subjects in the lowest (<44 bpm) versus the highest (>61 bpm) quartile of HRR (14.4% versus 4.1%, p<0.001). In multivariable logistic regression models adjusted for established CHD risk factors, inflammatory markers, and exercise capacity, subjects in the lowest quartile of HRR (<44 bpm) were 1.50 times (95% CI: 1.13-2.00) more likely to have carotid atherosclerosis than subjects in the highest quartile (HRR>61 bpm).

CONCLUSIONS

Slow heart rate recovery after exercise, an index of decreased parasympathetic activity, is associated with carotid atherosclerosis independent of established risk factors in middle-age men.

Wavelength-division-multiplexing optical packet switch with heterogeneous wavelength conversion capabilities

Among the wavelength-division-multiplexing (WDM) optical packet switches (OPSs) using wavelength converters (WCs), a shared-per-node switch architecture has been considered as a way to utilize WCs efficiently. We propose a new switch control algorithm for the architecture. The proposed algorithm, different from previous algorithms, focuses on using the heterogeneous WC blocks (HeWCBs), where a HeWCB consists of WCs with different wavelength conversion degrees (WCDs). The results show that the WDM OPS architecture using HeWCBs reduces the number of WCs with a higher WCD, while minimizing the packet loss from wavelength contention at outbound links.

Production of cloned horse foals using roscovitine-treated donor cells and activation with sperm extract and/or ionomycin

We evaluated the effect of different activation treatments on the production of blastocysts and foals by nuclear transfer. Donor cells were prepared using roscovitine treatment, which has previously been associated with increased production of viable offspring. All activation treatments were followed by culture in 6-dimethylaminopurine (6-DMAP) for 4 h. In experiment 1, blastocyst production after activation by injection of sperm extract followed by treatment with ionomycin was significantly higher than that for activation with a serial treatment of ionomycin, 6-DMAP, and ionomycin (12.5 vs 2.8%; P < 0.05) and tended to be higher than that for injection of sperm extract alone (3.4%; P = 0.07). In experiment 2, there were no significant differences in blastocyst development among treatments with ionomycin once or twice, sperm extract then ionomycin, or ionomycin then sperm extract (range 4.6-7.3%). Overall, transfer of 26 blastocysts resulted in 16 pregnancies (62%) and 9 live foals (35% of transferred embryos). Treatment with sperm extract followed by ionomycin produced a live foal rate per embryo transferred of 5/10 (50%). One foal died of pneumonia 48 h post partum and one foal died at 1 week of age after complications during induction of anesthesia; the remaining seven foals are currently 10-14 months of age.

Effect of holding technique and culture drop size in individual or group culture on blastocyst development after ICSI of equine oocytes with low meiotic competence

The effect of medium-to-embryo ratio on blastocyst development of equine embryos from oocytes with compact cumuli was evaluated in the present experiment. In addition, two methods for holding oocytes before in vitro maturation were compared. In Experiment 1, oocytes cultured with roscovitine for 16-18h before maturation were fertilized by intracytoplasmic sperm injection and cultured individually in 2.5, 5, 10 or 50microl droplets. In Experiment 2, oocytes were either cultured with roscovitine or held in a modified M199 with 20% serum at room temperature (EH treatment) for 16-18h, then matured, fertilized and cultured in groups at 5microl medium per embryo. In Experiment 3, oocytes were held in the EH treatment, then were matured and fertilized. In Study 3.1, injected oocytes were cultured individually in drop sizes as for Experiment 1; in Study 3.2, groups of 2-7 oocytes were cultured in fixed drop sizes of 5 or 50microl. Blastocyst development rates of individually-cultured embryos were not significantly different among drop sizes in either Experiment 1 or 3 (15-29%). In Experiment 2, blastocyst rates were not significantly different between holding treatments (17-23%). In Experiment 3, for group-cultured oocytes, blastocyst development was not significantly different between 5 and 50microl drops (39 and 27%, respectively). In conclusion, compact-cumulus oocytes may be effectively held in the EH treatment before maturation, and single culture of equine embryos yields acceptable blastocyst development. The greatest blastocyst rate (39%) was obtained with group culture in a 5microl droplet.

Is metabolic syndrome a risk factor for colorectal adenoma?

BACKGROUND AND AIMS

Epidemiologic studies provide evidence for a link between obesity or diabetes and the risk for colorectal cancer. However, there is a lack of information about the relationship between metabolic syndrome and colorectal adenoma. Therefore, we investigated whether metabolic syndrome is a risk factor for colorectal adenoma.

METHODS

We did a study for consecutive subjects who underwent colonoscopy as a screening exam at the Center for Health Promotion, Samsung Medical Center, from March 2004 to December 2005. According to the modified ATP III criteria, metabolic syndrome was diagnosed. We classified a total of 2,531 subjects into the adenoma group (n = 731) and the control group (n = 1,800), including normal colonoscopic finding, nonpolyp benign lesions, or histologically confirmed hyperplastic polyp.

RESULTS

The prevalence for metabolic syndrome was 17% in the adenoma group and 11% in the control group. On the multiple logistic regression analyses, metabolic syndrome was found to be associated with an increased risk of colorectal adenoma (odds ratio, 1.51; 95% confidence interval, 1.18-1.93). Also, waist circumference among the individual components of metabolic syndrome was an independent risk factor for colorectal adenoma. An increased risk for metabolic syndrome was more evident for proximal than distal colon, for multiple (>/=3), and for advanced adenoma in the adenoma group.

CONCLUSION

Metabolic syndrome was associated with colorectal adenoma. Abdominal obesity of the individual components of metabolic syndrome was an important risk factor for colorectal adenoma.

Ejaculate and type of freezing extender affect rates of fertilization of horse oocytes in vitro

In vitro fertilization (IVF) was performed on in vitro-matured equine oocytes in three experiments. Frozen-thawed sperm were prepared using swim-up separation and heparin treatment. In Experiment 1, fertilization was achieved with sperm from only one frozen ejaculate of four obtained from the same stallion. Within this ejaculate, fertilization rates were higher with fresh media, as compared to media held for 6-8 days before use (39.6% versus 7.3%, respectively; P<0.001). The type of bovine serum albumin used affected fertilization rates (4% versus 39.6%; P<0.001). To determine if IVF rates were influenced by factors associated with the freezing process (Experiment 2), a single ejaculate from a second stallion was frozen using eight variations in timing of steps in the freezing protocol. There were no differences among treatments in fertilization rates (range, 0-3%). In Experiment 3, fertilization rates of semen frozen in an extender containing 21.5% egg yolk were lower than fertilization rates of semen from the same ejaculate but frozen with a 3% egg-yolk extender (0% versus 15%, respectively; P<0.01). We inferred that rates of equine IVF with frozen-thawed sperm were influenced by ejaculate, the composition and age of the media used, and freezing extender. To our knowledge, this is the first report of ejaculate or extender differences affecting in vitro fertilization in this species. These factors may help to explain the great variability in fertilization rates reported with equine IVF, both among and within laboratories.

In vitro-produced equine embryos: production of foals after transfer, assessment by differential staining and effect of medium calcium concentrations during culture

Viability of equine embryos produced by oocyte maturation, intracytoplasmic sperm injection and embryo culture to the blastocyst stage in vitro was evaluated after transfer of embryos to recipient mares. No pregnancies were produced after transfer of five blastocysts that had been cultured in G media. Transfer of 10 blastocysts cultured in modified DMEM/F-12 medium produced five pregnancies and three live foals; the two lost pregnancies developed only trophoblast (based on transrectal ultrasonography). To evaluate the status of the inner cell mass, equine blastocysts produced in vivo and in vitro were assessed after differential staining. A discrete inner cell mass could not be appreciated in blastocysts of either source after staining; this was attributed to the presence of a network of cells within the trophoblastic vesicle. Because increased medium calcium concentrations have been reported to decrease the incidence of trophoblast-only pregnancy after transfer of equine nuclear transfer embryos, we investigated the effect of increased calcium concentrations during oocyte maturation or during embryo culture. Increasing calcium concentration of culture medium from 2 to 5.6mM during in vitro oocyte maturation did not affect maturation rate (75 and 68%, respectively) or blastocyst development after fertilization (23 and 27%). However, increasing calcium concentration (from 1.3 to 4.9 mM) of medium used for embryo culture significantly decreased blastocyst development (27% versus 13%, respectively) and adversely affected embryo morphology. More work is needed to optimize culture systems for in vitro production of equine embryos.

Association between cardiorespiratory fitness and prevalence of carotid atherosclerosis among men with hypertension

BACKGROUND

Carotid atherosclerosis is a risk factor for cardiovascular mortality and may represent hypertension-related target organ damage. Cardiorespiratory fitness is inversely associated with cardiovascular mortality in hypertensive men. We tested the hypothesis that higher levels of cardiorespiratory fitness are inversely associated with the prevalence of carotid atherosclerosis in a cross-sectional study of 2532 (53.2 +/- 8.5 years old) hypertensive men.

METHODS

Men with hypertension (defined as systolic over diastolic blood pressure of > or = 140/90 mm Hg or self-reported use of antihypertensive medication) underwent maximal exercise treadmill testing with expired gas analysis. Carotid atherosclerosis was defined as stenosis of > 25% and/or intima-media thickness of > 1.2 mm using B-mode ultrasonography.

RESULTS

The overall prevalence of carotid atherosclerosis was 13.4%. The prevalence of carotid atherosclerosis was inversely associated with cardiorespiratory fitness category (low 22.5%, moderate 10.9%, and high 8.7%; P < .001 for trend). After adjusting for established risk factors, high and moderate fitness were associated with lower odds ratios for having carotid atherosclerosis, 0.63 (95% CI 0.47-0.85) and 0.62 (95% CI 0.41-0.92), respectively, compared with low fitness. Each metabolic equivalent increment higher peak oxygen uptake was associated with 11% (odds ratio 0.89, 95% CI 0.82-0.97) lower prevalence of carotid atherosclerosis.

CONCLUSIONS

These results suggest that higher levels of cardiorespiratory fitness are inversely associated with the prevalence of carotid atherosclerosis in hypertensive men.

A promoter nucleotide variant of the dendritic cell-specific DCNP1 associates with serum IgE levels specific for dust mite allergens among the Korean asthmatics

Dendritic cells (DCs), the most abundant antigen-presenting cells in the lung, have been drawing attention for their roles in specific allergic responses to aeroallergens with support of Th lymphocytes, and in persistent inflammatory changes in allergic asthma. To identify genetic factors that may be involved in the asthma susceptibility and development of the disease phenotypes, we examined association of DC-specific DCNP1 polymorphisms with the disease risk. The case-control study revealed association of the nucleotide variants with serum immunoglobulin E (IgE) levels specific for Dermatophagoides farinae (Der f 1) and Dermatophagoides pteronyssinus (Der p 1), major aeroallergens of dust mites, among subjects with asthma. In particular, the T-allele-carrying genotype frequencies for one of the variants (c.-1289C>T) located in the promoter region were found increased in the asthmatic group with low levels of the mite-specific IgE (odds ratio (OR)=0.63 (0.48-0.83) for Der p 1). Results from functional analyses indicated that the promoter variant would affect the gene expression by modulating DNA-protein interaction. We propose that the genetic polymorphism of DCNP1 may influence production of specific IgE by altering DC functions in the mite allergen presenting and/or processing. The functional relevance of the genetic variation would provide an important insight into the genetic basis of allergic response to the mite antigens.

Vertebroplasty: magnetic resonance findings related to cement leakage risk

PURPOSE

To find magnetic resonance (MR) findings predicting cement leakage in patients receiving percutaneous vertebroplasty (PVP) due to osteoporotic compression fractures.

MATERIAL AND METHODS

MR was done in 43 patients (age 52-89 years) before PVP (56 vertebrae), which was done via a bipedicular approach with fluoroscopic monitoring. Shortly after the procedure, a non-contrast-enhanced computed tomography (CT) scan was done at the vertebroplasty sites for evaluation of bone cement leakage. The following MR findings of fractured vertebral bodies were retrospectively reviewed for correlation with leakage risk: severity of bone-marrow edema, presence of a T2-weighted low-signal-intensity line, percentage residual vertebral body height, presence of either a vacuum or cystic change within the vertebral body, and presence of a cortical disruption.

RESULTS

After PVP, cement leakage was detected in 35 vertebrae (62.5%). Leakage was most frequently observed in the anterior external vertebral venous plexus (46%). Cement leakage rate increased when there was a cortical disruption (P = 0.037), especially at the endplates, while it decreased when there was a vacuum or a cystic change within the fractured vertebra (P = 0.019). Other MR findings were not related to the risk of cement leakage.

CONCLUSION

The risk of cement leakage in PVP increases when MR shows cortical disruption in a fractured vertebral body, especially at the endplates. It decreases when MR shows a vacuum or cystic change within the body.

Hepatitis B virus seropositivity and the risk of stroke and myocardial infarction

BACKGROUND AND PURPOSE

Conflicting findings on the possible association between hepatitis B virus surface antigen (HBsAg) seropositivity and atherosclerosis have been reported. We examined the association between HBsAg seropositivity and cardiovascular diseases in a cohort of Koreans with a high prevalence of hepatitis B viral infection.

METHODS

Men (N=521 421) aged 30 to 64 years were categorized into 4 groups according to HBsAg seropositivity status and the presence of liver dysfunction were followed up from 1990 to 2001 for both fatal and nonfatal myocardial infarctions (MIs) and strokes. The associations of HBsAg seropositivity with these cardiovascular diseases were examined with a Cox proportional-hazards model.

RESULT

Overall, HBsAg seropositivity was associated with a decreased risk of ischemic stroke and MI and an increased risk of hemorrhagic stroke, with multivariable-adjusted hazard ratios (95% CIs) of 0.79 (0.68, 0.90), 0.74 (0.62, 0.87), and 1.33 (1.15, 1.52), respectively. Risks for stroke and MI were similar between HBsAg-seronegative and HBsAg-seropositive men in the absence of liver dysfunction, whereas men with both HBsAg seropositivity and liver dysfunction had a higher risk of hemorrhagic stroke and lower risks of ischemic stroke and MI compared with HBsAg-seronegative men.

CONCLUSIONS

The association between HBsAg seropositivity and stroke and MI appears to be secondary to the liver dysfunction associated with hepatitis B viral infection. HBsAg seropositivity itself did not appear to play an important role in atherothrombosis through inducing a proinflammatory effect.

[The age-specific seroprevalence of hepatitis A virus antibody in Korea]

BACKGROUNDS AND AIMS

The epidemiology of hepatitis A is associated with socioeconomic and hygiene status. Recently, the prevalence of hepatitis A in young adults has been steadily increasing in Korea. This study is to investigate the age-specific seroprevalence of hepatitis A virus in Korea.

METHODS

Stored sera from 250 healthy adult subjects who visited the health promotion center in Samsung Medical Center between July and August 2006 were tested for IgG hepatitis A virus antibody (anti-HAV).

RESULTS

The prevalence of anti-HAV was 2%, 72%, 92%, 94%, 100% in 20's, 30's, 40's, 50's, and 60's, respectively. The prevalence of anti-HAV was significantly lower in subjects below age 40 compared to those above 40 (37.0% vs. 95.3%, p<0.001). The seroprevalence was higher in area outside of Seoul compared to those living in Seoul in age group below 40 (25.6% vs. 55.6%, p=0.01). In Seoul area, the prevalence was significantly lower in Kangnam-Gu, Seocho-Gu, and Songpa-Gu district compared to the other areas of Seoul in the age group below 40 (20.0% vs. 42.1%, p<0.05).

CONCLUSION

The seroprevalence of hepatitis A virus antibody in Korean population below 40 is quite low and immunity to hepatitis A virus in those subjects can be a public health issue. In view of changing seroepidemiology, a policy for hepatitis A vaccination in population below 40 might be warranted.

Impact of NAD(P)H oxidase p22 phox gene polymorphism on vascular aging in Korean centenarian and nonagenarian

BACKGROUND

Oxidative stress, the imbalance between production and removal of reactive oxygen species (ROS), is implicated in the process of cardiovascular aging. Membrane-associated NAD(P)H oxidase system is the most important source of ROS in vascular cells. p22(phox), a critical component of the NAD(P)H oxidase, has a polymorphic site on exon 4, associated with variable enzyme activity. The goal of this study is to investigate the effect of the p22(phox) C242T polymorphism on cardiovascular aging.

METHODS

We investigated, in a cross-sectional study, the distribution of the p22(phox) genotypes and its impact on vascular aging in elderly Korean subjects (N=123, mean age+/-SD: 97.0+/-5.0). p22(phox) C242T polymorphism was determined by PCR and restriction fragment length polymorphism analysis. The p22(phox) genotype and allele frequencies were also compared with younger Korean subjects (N=363, mean age+/-SD: 49.0+/-10.3).

RESULTS

No significant difference was identified in p22(phox) genotype frequency according to the subject's age. However, the prevalence of CT+TT genotype was significantly less frequent in normotensive extremely elderly compared with younger subjects. Furthermore, the prevalence of the CT+TT genotype was significantly more frequent in hypertensive subjects (21.9%) than in the normotensive group (6.0%, P=0.016) in extremely elderly subject. The association was more significant in systolic hypertension rather than diastolic hypertension. Mean systolic blood pressure and pulse pressure were also significantly higher in subjects with CT+TT genotype. In contrast, there was no significant association between p22(phox) genotype and hypertension in younger-aged group.

CONCLUSION

These results suggest an association between the p22(phox) C242T polymorphism and vascular aging, which might be mediated by the increase of oxidative stress.

Emerging invasive liver abscess caused by K1 serotype Klebsiella pneumoniae in Korea

OBJECTIVES

The high incidence of invasive liver abscess caused by Klebsiella pneumoniae in Taiwan, contrasted with the rareness of this disease in Western countries, has aroused special interest. There have been few detailed reports from other Asian countries. To investigate a current epidemiology of K. pneumoniae liver abscess in Korea and to determine K serotype distribution in K. pneumoniae strains causing liver abscess, we performed a nationwide prospective study.

METHODS

Community-acquired, culture-proven liver abscess cases were enrolled between 2004 and 2005. Etiologies and clinical features were analyzed. K. pneumoniae isolates were serotyped according to K antigen. Meta-analysis was done to determine the time trend of the etiologies of liver abscess in Korea.

RESULTS

Out of 371 cases collected prospectively, 290 (78.2%) were caused by K. pneumoniae. Most K. pneumoniae liver abscesses were monomicrobial. Diabetes mellitus was the most common underlying disease (39.9%). Distant metastatic infections were frequently observed (8.7%). magA PCR revealed that 95 (59.4%) out of 160 K. pneumoniae isolates belonged to the K1 serotype.

CONCLUSIONS

Our study indicates that K. pneumoniae has emerged as a major etiologic agent of liver abscess in Korea, and these emerging infections seem to be attributable to invasive K. pneumoniae strains with capsular K1 serotype.

Production of horse foals via direct injection of roscovitine-treated donor cells and activation by injection of sperm extract

We evaluated the effects of different donor cell treatments and activation methods on production of blastocysts after equine nuclear transfer. Nuclear transfer was performed by direct injection of donor cells, using a piezo drill, and standard activation was by injection of sperm factor followed by culture with 6-dimethylaminopurine. There was no difference in blastocyst development between embryos produced with roscovitine-treated or confluent donor cells (3.6% for either treatment). Addition of injection of roscovitine or culture with cycloheximide at the time of activation did not affect blastocyst development. Overall, transfer of eight blastocysts produced using roscovitine-treated donor cells and our standard activation protocol yielded three pregnancies, of which two (25% of transferred embryos) resulted in delivery of viable foals. Flow cytometric evaluation showed that roscovitine treatment significantly increased the proportion of cells classified as small, in comparison to growth to confluence or serum deprivation, but did not significantly affect the proportion of cells in G0/G1 (2N DNA content). Transfer of one blastocyst produced using roscovitine-treated donor cells, with addition of roscovitine injection at activation, yielded one pregnancy which was lost before 114 days' gestation. Transfer to recipients of two blastocysts produced using confluent donor cells with addition of cycloheximide at activation gave no resulting pregnancies. We conclude that roscovitine treatment of donor cells yields equivalent blastocyst production after nuclear transfer to that for confluent donor cells, and that direct injection of roscovitine-treated donor cells, followed by activation using sperm extract, is compatible with efficient production of viable cloned foals.