Is the medical loss ratio a good target measure for regulation in the individual market for health insurance?

Effective January 1, 2011, individual market health insurers must meet a minimum medical loss ratio (MLR) of 80%. This law aims to encourage 'productive' forms of competition by increasing the proportion of premium dollars spent on clinical benefits. To date, very little is known about the performance of firms in the individual health insurance market, including how MLRs are related to insurer and market characteristics. The MLR comprises one component of the price-cost margin, a traditional gauge of market power; the other component is percent of premiums spent on administrative expenses. We use data from the National Association of Insurance Commissioners (2001-2009) to evaluate whether the MLR is a good target measure for regulation by comparing the two components of the price-cost margin between markets that are more competitive versus those that are not, accounting for firm and market characteristics. We find that insurers with monopoly power have lower MLRs. Moreover, we find no evidence suggesting that insurers' administrative expenses are lower in more concentrated insurance markets. Thus, our results are largely consistent with the interpretation that the MLR could serve as a target measure of market power in regulating the individual market for health insurance but with notable limited ability to capture product and firm heterogeneity.

Loss of intrahepatic HBsAg expression predicts sustained response to peginterferon and is reflected by pronounced serum HBsAg decline

There is a lack of knowledge regarding the effect of peginterferon (PEG-IFN) on the expression of intrahepatic hepatitis B core and surface antigen (HBcAg and HBsAg) in chronic hepatitis B (CHB) and its relation with response to therapy. Fifty-two HBeAg-positive and 67 HBeAg-negative CHB patients with paired liver biopsies taken at baseline and after 1 year of PEG-IFN therapy were studied. After PEG-IFN therapy, HBeAg-negative patients showed a significant reduction in both intrahepatic HBcAg (P = 0.04) and HBsAg expression (P < 0.001). In contrast, a reduction in intrahepatic HBcAg expression was not observed in HBeAg-positive patients, while a trend in reduction of intrahepatic HBsAg staining was found (P = 0.09). Post-treatment, 7 (13%) HBeAg-positive and 9 (14%) HBeAg-negative patients had no expression of intrahepatic HBsAg. Patients without any intrahepatic HBsAg expression post-treatment were more likely to achieve a combined response (HBeAg loss with hepatitis B virus (HBV) DNA <2000 IU/mL for HBeAg -positive and HBV DNA <2000 IU/mL and normal alanine aminotransferase for HBeAg-negative CHB): 71% vs 5% for HBeAg-positive (P < 0.001) and 60% vs 16% for HBeAg-negative patients (P = 0.004), respectively. Moreover, a more profound decline of serum HBsAg was observed in patients with absence of intrahepatic HBsAg staining (3.1 vs 0.4 log IU/mL, P < 0.001 and 1.7 vs 0.4 log IU/mL, P = 0.005 for HBeAg-positive and HBeAg-negative CHB, respectively). In conclusion, PEG-IFN reduces expression of intrahepatic HBsAg. Loss of HBsAg as assessed by immunohistochemistry from the liver predicts a sustained response and is reflected in a pronounced serum HBsAg decline.

Development of ileal cytokine and immunoglobulin expression levels in response to early feeding in broilers and layers

Provision of feed in the immediate posthatch period may influence interaction between intestinal microbiota and immune system, and consequently immunological development of the chick. This study addressed ileal immune development in response to early feeding in 2 chicken breeds selected for different production traits: broilers and layers. Chicks of both breeds either received feed and water immediately posthatch or were subjected to a 72-h feed and water delay. Ileal cytokine and immunoglobulin mRNA expression levels were determined at different time points. Effects of early feeding were limited, but breeds differed strikingly regarding cytokine and immunoglobulin expression levels. Cytokine expression levels in broilers were low compared with layers and showed a transient drop in the second to third week of life. In contrast, broilers showed considerably higher expression levels of IgA, IgM, and IgY. These findings indicate that the 2 breeds use different immune strategies, at least on the ileal level.

Polymorphisms of HLA-DP are associated with response to peginterferon in Caucasian patients with chronic hepatitis B

BACKGROUND

Polymorphisms of the HLA-DP gene are associated with the natural clearance of the hepatitis B virus in Asian patients.

AIM

To investigate the association of HLA-DP polymorphisms with response to peginterferon (PEG-IFN) in Caucasian chronic hepatitis B (CHB) patients.

METHODS

We studied 262 Caucasian chronic hepatitis B patients infected with HBV genotype A or D, treated with PEG-IFN for 1 year in two randomised controlled trials (HBV 99-01 and PARC study). Response was defined as an HBV DNA <2000 IU/mL at 6 months post-treatment. Variations at HLA-DPA1 and HLA-DPB1 were genotyped.

RESULTS

Of the 262 patients, 58% was HBeAg-positive and HBV genotype A and D was observed in 32% and 68%, respectively. At 6 months post-treatment, 57 (22%) patients had achieved an HBV DNA <2000 IU/mL. HLA-DPB1 was independently associated with virological response [adjusted odds ratio (OR) 1.8, 95% confidence interval (CI):1.1-3.0, P = 0.025], and with an undetectable HBV DNA (adjusted OR 2.4 95% CI: 1.2-4.7, P = 0.015) when adjusted for HBeAg status and other known response modifiers. In HBeAg-positive patients, combined HBeAg seroconversion with HBV DNA <2000 IU/mL was increasingly observed with each addition of an HLA-DPB1 G-allele (adjusted OR 2.7, 95% CI: 1.2-5.9, P = 0.012). Furthermore, HLA-DPA1 and HLA-DPB1 haplotype block GG showed comparable results for virological and combined response.

CONCLUSION

In this large cohort of Caucasian chronic hepatitis B patients infected with HBV genotypes A or D, polymorphisms of HLA-DP are independently associated with both virological and serological response to PEG-IFN therapy at 6 months post-treatment.

Marital Disruption and Health Insurance

Despite the high levels of marital disruption in the United States and the fact that a significant portion of health insurance coverage for those less than age 65 is based on family membership, surprisingly little research is available on the consequences of marital disruption for the health insurance coverage of men, women, and children. We address this shortfall by examining patterns of coverage surrounding marital disruption for men, women, and children, further subset by educational level. Using the 1996, 2001, and 2004 panels of the Survey of Income and Program Participation (SIPP), we find large differences in health insurance coverage across marital status groups in the cross-section. In longitudinal analyses that focus on within-person change, we find small overall coverage changes but large changes in type of coverage following marital disruption. Both men and women show increases in private coverage in their own names, but offsetting decreases in dependent coverage tend to be larger. One surprising result is that dependent coverage for children also declines after marital dissolution, even though children are still likely to be eligible for that coverage. Children and (to a lesser extent) women show increases in public coverage around the time of divorce or separation. We also find that these patterns differ by education. The most vulnerable group appears to be lower-educated women with children because the increases in private, own-name, and public insurance are not large enough to offset the large decrease in dependent coverage. As the United States implements federal health reform, it is critical that we understand the ways in which life course events—specifically, marital disruption—shape the dynamic patterns of coverage.

[Use of negative pressure wound therapy on surgical incisions (prevena™) after surgery of pectus deformities reduces wound complications]

INTRODUCTION

Pectus surgery can lead to postoperative wound complications in some cases. The purpose of this study is to determine whether preventive negative pressure wound therapy (NPWT) could reduce wound complications after open pectus surgery.

MATERIAL AND METHODS

100 patients after open procedure for the treatment of pectus excavatum or pectus carinatum in the years 2010 to 2012 were retrospectively analysed. 50 patients treated with Prevena™ (KCI Medical Products GmbH, Wiesbaden, Germany) were compared with 50 patients whose wounds were covered with OPSITE® film (Smith & Nephew, Hamburg, Germany). Wound closure was performed following a standard procedure as well as the placement of subcutaneous drains. Therefore two comparable groups of patients were formed and analysed by standardised parameters. The wound dressing was placed epicutaneously immediately after wound closure in the operating room and removed after 5 days in each case. Follow-ups were performed immediately after removal of the wound dressing, at the time of discharge from hospital as well as 6 and 12 weeks after operation. The wounds were checked for tenderness, pain, secretion, redness and fistulas.

RESULTS

The Prevena group showed 10 % wound complications which needed operative treatment, whereas the OPSITE group showed complications in 24 %. Some patients who were treated with Prevena showed superficial skin lesions at the rim of the foam and the film. All of these lesions healed well.

CONCLUSION

Treating wounds postoperatively with preventive measures (NPWT) showed a remarkable reduction of wound complications following open pectus surgery whereas statistically the difference was not significant (p = 0.074).

Did they come to the dance? Insurer participation in exchanges

OBJECTIVES

An important feature of the Affordable Care Act is the creation of insurance exchanges, which are organized marketplaces through which individuals could begin to shop for and purchase coverage beginning in 2014. This study analyzes the decisions of new insurers and incumbent insurers already operating in a major market within a state to participate in state and federally facilitated exchanges.

STUDY DESIGN

Utilizing secondary data from the National Association of Insurance Commissioners* and government websites, we describe each state's insurance market in 2012, summarizing the number of incumbent insurers by size and operations in the individual market segment. Next, we investigate the organizational, market, and policy-related factors associated with incumbent insurers' participation decisions. Finally, we discuss the entry patterns of new insurers and briefly assess their potential impact on the market.

METHODS

We use multivariate regression analysis to identify the organizational, market, and policy-related factors related to insurer participation in exchanges.

RESULTS

Only 10% of incumbent insurers are participating in exchanges in 2014, although considerable variation exists across states. Participation is more prevalent among larger insurers, local and regional insurers, and those with prior experience in other market segments in the same state. The entry of newly formed organizations, such as cooperatives (co-ops), and of existing insurers into new states is modest.

CONCLUSIONS

Robust participation of insurers is an important prerequisite to ensure competition in health insurance markets. Exchange administrators will need to better understand the strategic or operational reasons why insurers chose not to participate in the individual market exchanges in 2014. *The NAIC does not endorse any analysis or conclusions based upon the use of its data.

Predictors associated with treatment initiation and switch in a real-world chronic hepatitis B population from five European countries

In Europe, healthcare systems differ between countries and different factors may influence Chronic hepatitis B (CHB) treatment choices in different counties. This analysis from a prospective, longitudinal, non-interventional study in five EU countries aimed to explore determinants associated with treatment initiation or switch in patients with CHB. A total of 1267 adult patients with compensated CHB in Germany, France, Poland, Romania and Turkey were prospectively followed for up to 2 years (March 2008-December 2010). Determinants of treatment initiation or switch were analysed using multivariate Cox proportional hazards regression. Median time since CHB diagnosis was 2.6 (0-37.7) years. Among 646 treatment-naïve patients, the probability of treatment initiation during follow-up was higher: in Germany (P = 0.0006), Poland (P < 0.0001) and Romania (P = 0.0004) compared with Turkey; in patients with alanine transaminase (ALT) 1-2 × upper limit of normal (ULN) (P = 0.0580) or >2 × ULN (P = 0.0523) compared with ALT ≤ 1 × ULN; and in patients with hepatitis B virus (HBV) DNA ≥ 2000 IU/mL (P < 0.0001) compared with HBV DNA <2000 IU/mL or undetectable. Among 567 treated patients, 87 switched treatment during follow-up. The probability of treatment switch was higher: in France (P = 0.0029), Germany (P = 0.0078) and Poland (P = 0.0329) compared with Turkey; and in patients with HBV DNA <2000 (P < 0.0001) or ≥ 2000 IU/mL (P < 0.0001), compared with undetectable. Viral load and ALT level were identified as the major drivers of treatment initiation. HBV DNA level was also a significant determinant of treatment switch. Results were statistically different across EU countries.

Ancient microbial activity recorded in fracture fillings from granitic rocks (Äspö Hard Rock Laboratory, Sweden)

Fracture minerals within the 1.8-Ga-old Äspö Diorite (Sweden) were investigated for fossil traces of subterranean microbial activity. To track the potential organic and inorganic biosignatures, an approach combining complementary analytical techniques of high lateral resolution was applied to drill core material obtained at -450 m depth in the Äspö Hard Rock Laboratory. This approach included polarization microscopy, time-of-flight secondary ion mass spectrometry (ToF-SIMS), confocal Raman microscopy, electron microprobe (EMP) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The fracture mineral succession, consisting of fluorite and low-temperature calcite, showed a thin (20-100 μm), dark amorphous layer lining the boundary between the two phases. Microscopic investigations of the amorphous layer revealed corrosion marks and, in places, branched tubular structures within the fluorite. Geochemical analysis showed significant accumulations of Si, Al, Mg, Fe and the light rare earth elements (REE) in the amorphous layer. In the same area, ToF-SIMS imaging revealed abundant, partly functionalized organic moieties, for example, C(x)H(y)⁺, C(x)H(y)N⁺, C(x)H(y)O⁺. The presence of such functionalized organic compounds was corroborated by Raman imaging showing bands characteristic of C-C, C-N and C-O bonds. According to its organic nature and the abundance of relatively unstable N- and O- heterocompounds, the organic-rich amorphous layer is interpreted to represent the remains of a microbial biofilm that established much later than the initial cooling of the Precambrian host rock. Indeed, δ¹³C, δ¹⁸O and ⁸⁷Sr/⁸⁶Sr isotope data of the fracture minerals and the host rock point to an association with a fracture reactivation event in the most recent geological past.

Declines in employer-sponsored insurance between 2000 and 2008: examining the components of coverage by firm size

OBJECTIVE

To examine trends in employer-sponsored health insurance coverage rates and its associated components between 2000 and 2008, to provide a baseline for later evaluations of the Affordable Care Act, and to provide information to policy makers as they design the implementation details of the law.

DATA SOURCES

Private sector employer data from the 2000, 2001, and 2008 Medical Expenditure Panel Survey-Insurance Component (MEPS-IC).

STUDY DESIGN

We examine time trends in employer offer, eligibility, and take-up rates. We add a new dimension to the literature by examining dependent coverage and decomposing its trends. We investigate heterogeneity in trends by firm size.

DATA COLLECTION

The MEPS-IC is an annual survey, sponsored by the Agency for Healthcare Research and Quality and conducted by the U.S. Census Bureau. The MEPS-IC obtains information on establishment characteristics, whether an establishment offers health insurance, and details on up to four plans.

PRINCIPAL FINDINGS

We find that coverage rates for workers declined in both small and large firms. In small firms, coverage declined due to a drop in both offer and take-up rates. In the largest firms, offer rates were stable and the decline was due to falling take-up rates. In addition, enrollment shifted toward single coverage and away from dependent coverage in both small and large firms. For small firms, this shift was due to declining offer and take-up rates for dependent coverage. In large firms, offers of dependent coverage were stable but take-up rates dropped. Within the category of dependent coverage, the availability of employee-plus-one plans increased in all firm size categories, but take-up rates for these plans declined in small firms.

[SOPESS results and medical recommendations for school beginners]

AIM OF THE STUDY

The purpose of this study was to investigate the distribution of results of a developmental screening for school entry and procedures initiated by school doctors.

METHOD

Based on achievement in SOPESS of 372 children (188 female, 184 male) and the resulting recommendations of the school doctors, the distribution of frequencies in cross-classified tables was analysed, and Cramer's V was calculated.

RESULTS

No sex differences were found in early numeracy and coordination skills. Girls performed more frequently without any problems in the other domains assessed by SOPESS. Recommendations of school doctors referring to clarification of the finding or treatment are lower than the frequencies of critical results in SOPESS. This effect is especially critical in the domains of numeracy and attention. Critical SOPESS achievements in numeracy are found in 12% (attention: 10,2%) of the children, but only 0,5% (attention: 2,4%) are given recommendations for further treatment. An increase of documentation for parent counselling can be observed.

CONCLUSION

Documentation of the findings shows that medical recommendations for most domains of SOPESS are in accordance with frequencies of critical screening results. Further information is necessary for the domains of attention and numeracy.

Intraosseous epidermoid cysts of the hand skeleton: a series of eight patients

This paper reviews the clinical and radiographic features and treatment results in eight patients with intraosseous epidermoid cysts in the terminal phalanx of a finger seen over a period of 26 years. Data on age, sex, occupation, diagnostic findings, history of injury in six cases, treatment and follow-up were obtained by reviewing medical records and the histopathological findings using the hospital database. The most frequent symptoms of pressure pain, tenderness, redness and swelling occurred at a median time of 12 years after trauma. Male patients were mainly affected (7:1). In four the intraosseous epidermoid cysts were confused with other osteolytic diseases before surgery. Magnetic resonance imaging is recommended in any case of an osteolytic, expanding lesion, particularly in cases that are clinically and radiologically not obviously an intraosseous epidermoid cyst.

The impact of income on the weight of elderly Americans

This paper estimates the impact of income on the body weight and clinical weight classification of elderly Americans using a natural experiment that led otherwise identical retirees to receive significantly different Social Security payments based on their year of birth. We estimate models of instrumental variables using data from the National Health Interview Surveys and find no significant effect of income on weight. The confidence intervals rule out even moderate effects of income on weight and on the probability of being underweight or obese, especially for men. For example, they indicate that the income elasticity of body mass index is not greater in absolute value than 0.06 for men or 0.14 for women.

Polymorphisms of caffeine metabolism and estrogen receptor genes and risk of Parkinson's disease in men and women

Caffeine intake has been associated with a decreased risk of Parkinson's disease (PD) in men but the effect in women is less clear, and appears to be modified by use of post-menopausal estrogens. In a nested case-control study within the Nurses Health Study (NHS) and the Health Professionals Follow-up Study (HPFS), we examined associations between single nucleotide polymorphisms (SNPs) of caffeine metabolizing genes (CYP1A2 and NAT2) and estrogen receptors (ESR1 and ESR2), their interaction with caffeine intake and hormone replacement therapy (PMH) use (collected prospectively) and risk of PD. We matched 159 female cases to 724 controls and 139 male cases to 561 controls on birth year, source of DNA (blood or buccal smear), age and sex. The CYP1A2 rs762551 polymorphism (lower enzyme inducibility) was marginally associated with an increased risk of PD (RR, for increasing number of minor alleles=1.34; 95% CI 1.02, 1.78 in women, but not in men. None of the NAT2 (classified as slow vs. fast acetylator), ESR1 or ESR2 polymorphisms were significantly associated with an altered risk of PD. Marginally significant interactions were observed between caffeine intake and the ESR1 polymorphism rs3798577 (p=0.07) and ESR2 polymorphism rs1255998 (p=0.07). The observed increased risk of PD among female but not male carriers of the rs762551 polymorphism of CYP1A2 and the interactions of caffeine with ESR1 rs3798577 and ESR2 rs1255998 may provide clues to explain the relationship between gender, caffeine intake, estrogen status and risk of PD and need to be replicated.

Patient education and the impact of new medical research

We examine the impact that medical research published in peer-reviewed journals has on the practice of medicine. We exploit the release of a recent New England Journal of Medicine article which demonstrated that the risks of attempting a vaginal birth after having a previous C-section birth (VBAC) were higher than previously thought. We find that immediately following this article, the national VBAC rate dropped by 16% and this change was largest among more educated mothers, particularly those with a graduate degree.

[Development and standardisation of the social-pediatric screening SOPESS]

This paper offers insight into the development and the standardisation of the social-pediatric screening, SOPESS. The screening was developed for assessing children's developmental stages in the context of the health examination for school entry in North Rhine Westphalia. As the cutoff date regarding age, time of school entry has been rendered flexible, health examinations are due up to six months earlier than before. The screening's theoretical basis is described, its development and standardisation are presented, and its psychometric properties reported.

Crowd-out 10 years later: have recent public insurance expansions crowded out private health insurance?

Ten years ago, Cutler and Gruber [Cutler, D., Gruber, J., 1996. Does public health insurance crowdout private insurance? Quarterly Journal of Economics 111, 391-430] suggested that crowd-out might be quite large, but much subsequent research has questioned this conclusion. Our results using improved data and methods clearly show that crowd-out is still significant in the 1996-2002 period. This finding emerges most strongly when we consider family level measures of public insurance eligibility. We also find that recent anti-crowd-out provisions in public expansions may have had the opposite effect, lowering take-up by the uninsured faster than they lower crowd-out of private insurance.

Data needs for policy research on state-level health insurance markets

Private and public health insurance provision in the United States operates against a backdrop of 50 different regulatory environments in addition to federal rules. Through creative use of available data, a large body of research has contributed to our understanding of public policy in state health insurance markets. This research plays an important role as recent trends suggest states are taking the lead in health care reform. However, several important questions have not been answered due to lack of data. This paper identifies some of these areas, and discusses how the Agency for Healthcare Research and Quality could push the research agenda in state health insurance policy further by augmenting the market-level data available to researchers. As states consider new forms of regulation and assistance for their insurance markets, there is increased need for better warehousing and maintenance of policy databases.

Antagonistic expression of hepatitis C virus and alpha interferon in lymphoid cells during persistent occult infection

Detection of residual HCV in individuals with SVR after treatment of CHC can be significantly heightened by analyzing ex vivo mitogen-activated T and B lymphocytes and applying sensitive nucleic acid amplification assays. However, it remained unknown if synergistic activation of lymphocytes and monocytes would further augment HCV detection, if viral replication becomes universally upregulated in treated cells, and if examining sequential sera and lymphoid cells would improve detection of occult infection. Using paired sera and lymphoid cells collected 1 year apart from 17 individuals with normal liver enzymes for up to 72 months after SVR, it was found that simultaneous activation of lymphocytes and monocytes enhanced identification of silent HCV infection and revealed that in some cases monocytes were the principal immune cell type where HCV persisted. Testing of serial samples further increased detection of occult infection. Ultimately, by combining the above two approaches, all individuals with SVR were found to be silent carriers of HCV. Clonal sequencing revealed HCV variations in sera and lymphoid cells and evolution of viral genomes confirming ongoing virus replication. Surprisingly, similar to those with CHC, naive lymphoid cells from some individuals carried approximately 10(3) HCV copies/microg total RNA. HCV loads in naive lymphoid cells predetermined the outcome of ex vivo stimulation with respect to upregulation or inhibition of HCV replication. HCV RNA levels in occult infection were inversely proportional to the expression of IFNalpha and IFN-inducible MxA, but not to IFNgamma or tumour necrosis factor alpha in naive and mitogen-treated lymphoid cells.

High-protein nutrition during pregnancy and lactation programs blood pressure, food efficiency, and body weight of the offspring in a sex-dependent manner

Maternal low-protein diet during pregnancy is a risk factor for cardiovascular disease of the offspring in later life. The impact of high-protein diet during pregnancy on the cardiovascular phenotype of the offspring, however, is still unknown. We examined the influence of a high-protein diet during pregnancy and lactation on the renal, hemodynamic, and metabolic phenotype of the F1 generation. Female Wistar rats were either fed a normal protein diet (20% protein: NP) or an isocaloric high-protein diet (40% protein: HP) throughout pregnancy and lactation. At weaning, the offspring were fed with standard diet, and they were allocated according to sex and maternal diet to four groups: normal-protein male (NPm, n = 25), normal-protein female (NPf, n = 19), high-protein male (HPm, n = 24), high-protein female (HPf, n = 29). During the experiment (22 wk), the animals were characterized by repeated measurement of body weight, food intake, blood pressure, glucose tolerance, energy expenditure, and kidney function. At the end of the study period histomorphological analyses of the kidneys and weight measurement of reproductive fat pads were conducted. There were no differences in birth weight between the study groups. No influence of maternal diet on energy expenditure, glucose tolerance, and plasma lipid levels was detected. Blood pressure and glomerulosclerosis were elevated in male offspring only, whereas female offspring were characterized by an increased food efficiency, higher body weight, and increased fat pads. Our study demonstrates that a high-protein diet during pregnancy and lactation in rats programs blood pressure, food efficiency, and body weight of the offspring in a sex-dependent manner.

The effect of SCHIP expansions on health insurance decisions by employers

This study uses repeated cross-sectional data from the Medical Expenditure Panel Survey-Insurance Component (MEPS-IC), a large nationally representative survey of establishments, to investigate the effect of the State Children's Health Insurance Program (SCHIP) on health insurance decisions by employers. The data span the years 1997 to 2001, the period when states were implementing SCHIP. We exploit cross-state variation in the timing of SCHIP implementation and the extent to which the program increased eligibility for public insurance. We find evidence suggesting that employers whose workers were likely to have been affected by these expansions reacted by raising employee contributions for family coverage options, and that take-up of any coverage, generally, and family coverage, specifically, dropped in these establishments. We find no evidence that employers stopped offering single or family coverage outright.

Kinetics of protein tyrosine phosphorylation in sperm selected by binding to homologous and heterologous oviductal explants: how specific is the regulation by the oviduct?

Essential steps of the capacitation process take place in the oviductal isthmus. A crucial step in the process of capacitation is the phosphorylation of membrane proteins. The aims of this work were (1) to study the effect of dog sperm binding to oviductal epithelium on tyrosine phosphorylation and (2) to investigate the specificity of regulation of molecular changes by the oviduct of different species by comparing the numbers of canine sperm bound to heterologous (porcine) and homologous epithelium, and the kinetics of tyrosine phosphorylation. Semen was collected from four healthy dogs and washed through a Percoll gradient. Explants, small pieces of epithelium, were cut from porcine and estrous bitch oviducts. During 6 h of coincubation in Tyrode medium, the numbers of bound sperm were counted by microvideographic observation, and the state of tyrosine phosphorylation was determined immunocytochemically after 3, 30, 90, 180 and 360 min. Canine sperm bound in similar numbers to homologous and heterologous explants. Increasing tyrosine phosphorylation of tail proteins and subsequent phosphorylation of sperm head proteins were observed. Binding occurred mainly in sperm with non-phosphorylated heads (approximately 2% phosphorylated), while higher proportions of head-phosphorylated cells were found in unbound populations (approximately 40-60%;P<0.05). The head phosphorylation progressed significantly during incubation in unbound spermatozoa (P<0.05), while it was suppressed in bound suspensions. The rate of tyrosine phosphorylation of sperm tail proteins was higher in cells bound to explants than in unbound cells or in those incubated in control medium. There were no significant differences with respect to the kinetics of tyrosine phosphorylation between the two coincubation systems. These observations support the hypothesis that spermatozoa with non-phosphorylated heads preferentially attach to epithelial cells. Tyrosine phosphorylation of sperm head proteins and capacitation are delayed in spermatozoa in close contact with oviductal epithelium. This mechanism appears to be species-independent, as sperm bound similarly to pig and dog oviduct explants, and similar phosphorylation kinetics were observed in both types of tissue.

Regulation of capacitation of canine spermatozoa during co-culture with heterologous oviductal epithelial cells

Progress of essential steps of the capacitation is coordinated in the oviductal isthmus, where sperm are stored in close contact with the epithelium. A crucial capacitational event is the phosphorylation of sperm membrane proteins. Regulation of the tyrosine phosphorylation by the oviduct has not been examined in dog sperm yet. The aim of this work was to study the effect of dog sperm binding to porcine oviductal epithelium on capacitation-induced cellular and molecular changes. Epithelial cells were stripped from the oviducts of post-puberal sows and cultured for 5-7 days at 39 degrees C and 5% CO2 on Biomatrix-covered Chamber slides. Sperm washed through Percoll was co-incubated with the oviductal epithelium cell cultures in a bicarbonate Tyrode's medium. During co-incubation, sperm membrane changes, the state of tyrosine phosphorylation and motility were determined after 3, 30, 90, 180, 240 and 360 min. Significant increases in the percentage of capacitated and dead cells were observed in unbound sperm, while bound sperm remained uncapacitated, live and motile. An increasing tyrosine phosphorylation of tail proteins in bound, unbound and control sperm suspensions and a subsequent phosphorylation of head proteins in unbound and control sperm suspensions were observed. A significant difference regarding head phosphorylation (p < 0.05) was found between sperm bound to oviductal epithelium and unbound sperm. Binding occurred mainly in sperm with non- phosphorylated heads, while higher proportions of phosphorylated cells were found in unbound populations. The head phosphorylation progressed significantly during incubation in unbound spermatozoa (p < 0.05); however, it was suppressed in population of sperm attached to oviductal epithelium. Significant correlations between motility parameters related to hyperactivation and tail phosphorylation were found in unbound sperm. These observations support the hypothesis that spermatozoa with non-phosphorylated heads preferentially attach to epithelial cells. It can be concluded that tyrosine phosphorylation of head membrane proteins and capacitation are delayed in canine spermatozoa being in closed contact with oviductal epithelium.