Human parotid proline-rich proteins: correlation of genetic polymorphisms to dental caries

Parotid saliva contains a variety of proline-rich proteins. This study found that, among 306 children between the ages of 5 to 15 years, there is a significant increase in the decayed-missing-filled tooth surface (DMFS) score of the permanent teeth with age in children with the specific proline-rich protein phenotypes Pa and Pr. However, the increase in DMFS score of the permanent teeth of children was significantly greater in children with Pa+ and Pr22 than in those with the other phenotypes (Pa- or Pr11 and Pr12). The previously established close correlation between the Pa and Pr phenotypes and the genetic variants of salivary peroxidase (a powerful antibacterial system in the oral cavity) may provide an explanation for the relationship of certain proline-rich protein phenotypes to dental caries.     

Psychoeducational findings among children treated for phenylketonuria

Early treated phenylketonuric children who maintained a phe-restricted diet through age 10 were compared with those who discontinued the diet after age 6 on standardized tests of intelligence, school achievement, language, and perceptual skills. Mean IQ, reading, and spelling test scores improved between ages 6 and 10 for the on-diet children in comparison to those who were off diet. Mean scores on arithmetic, language, and perceptual skills, however, declined at a uniform rate for both groups. Children with PKU scored significantly lower than did their non-PKU siblings on tests of visual perception and visual-motor skills. We conclude that children with PKU should be maintained on a phe-restricted diet.     

Relative carriage rates of nuclear dehydrogenating clostridia in two populations of different colorectal cancer risk

Carriage of nuclear dehydrogenating clostridia has been associated with colon cancer and implicated in its aetiology. This study has compared the carriage of these organisms in a British population at high risk for the development of colon cancer with a low risk Nigerian population. Clostridia were found in all of the stools from both populations. Nuclear dehydrogenating clostridia were only found in the stools of the British subjects (32%). These results support the suggestion that the carriage rate of nuclear dehydrogenating clostridia in a population is related to the risk of colon cancer.     

Chromosome mapping ofSoa,a gene influencing gustatory sensitivity to sucrose octaacetate in mice

Strain distribution patterns among recombinant inbred strains suggested that a locus influencing taste sensitivity to sucrose octaacetate was on chromosome 6. A location forSoa was established by linkage analysis of behavioral and electrophoretic data from outbred and congenic strains and from test-cross progeny. Haplotyping of 41 outbred CFW-Cr animals with a cDNA probe showed perfect cosegregation ofSoa andPrp, a gene for salivary proline-rich proteins. Five of twelve B6. SW-Soa ^a strains were found to retainLdr-1, lactate dehydrogenase regulator-1, on chromosome 6 as an allelic passenger from the SWR/J donor strain (source of theSoa ^a Taster allele). Centimorgan distance was estimated using the ABP/Le linkage-testing strain (non-Taster,Soa ^b) and the SWR/J strain (Taster,Soa ^a) in a testcross breeding system. The data are consistent with a position for theSoa locus on mouse chromosome 6, 62 cM from the centromere.This research was supported in part by Grants DC00150 (G. W.) and DE003658 (E.A.A.). This paper is based on a thesis submitted to the Florida State University by the first author in partial fulfillment of the requirements for the Master of Sciences degree.     

Development of hatching blastocysts from immature human oocytes following in-vitro maturation and fertilization using a co-culture system

Recently, in-vitro maturation (IVM) of immature human oocytes recovered from non-stimulated follicles has been applied in the treatment of infertility. However, in previous reports, very few embryos cultured in conventional medium have reached the expanded blastocyst stage following in-vitro maturation and fertilization (IVM/IVF). The objective of this study was to investigate whether the developmental competence of human embryos following IVM/IVF could be enhanced by the use of a human ampullary cell co-culture system. Immature human oocytes were aspirated from small follicles at Caesarean section and then cultured in medium containing human menopausal gonadotrophin for 36 to 48 h, followed by insemination. Zygotes were randomly cultured either in conventional culture medium alone or in the co-culture system. Of 48 embryos cultured in conventional medium alone, all arrested at the 2-16- cell stage on day 3 after insemination. Of 46 embryos cultured in the co-culture system, 26 embryos (56.5%) arrested at the 2-16-cell stage. Six embryos (13%) developed to the morula stage. Fourteen embryos (30.4%) developed to expanded blastocysts and two blastocysts were hatching on day 7 after insemination. We conclude that co-culture significantly enhances the development of blastocysts in embryos resulting from IVM/IVF.      

Detection of chromosomes and estimation of aneuploidy in human spermatozoa using fluorescence in-situ hybridization

The development and application of fluorescence in-situ hybridization (FISH) has opened the way for comprehensive studies on numerical chromosome abnormalities in human spermatozoa. FISH can be rapidly applied to large numbers of spermatozoa and thus overcomes the major limitation of karyotyping spermatozoa after penetration of zona-free hamster oocytes. The simultaneous hybridization of two or more chromosome-specific probes to spermatozoa and subsequent detection of the bound probes using different fluorescent detection systems enables two or more chromosomes to be localized simultaneously in the same spermatozoon and provides a technique for undertaking reasonable estimates of aneuploidy. The most commonly used probes are those which bind to the centromeric region of specific chromosomes. Most studies to date have concentrated on estimating aneuploidy in spermatozoa from normospermic men, although reports are beginning to appear on aneuploidy in spermatozoa from subfertile and infertile men. Multi- probe FISH studies have generally reported disomy (hyperhaploidy) estimates of 0.05-0.2% per chromosome. There is preliminary evidence that some chromosomes such as X, Y and 21 are predisposed towards higher rates of non-disjunction during spermatogenesis. There are also suggestions of inter-donor variability in aneuploidy frequencies for specific chromosomes, although this requires confirmation in larger studies. While FISH is clearly a powerful technique that has many applications in reproductive medicine, it must also be realized that it does have limitations and the technology itself is still evolving and has yet to be fully validated on spermatozoa.      

Impact of PKU on the reproductive patterns in collaborative study families

Factors that relate to reproductive patterns in 129 families after the birth of a child with phenylketonuria (PKU) include birth order of the index child, age of the parents at the birth of the index child, and expressed intentions of the parents whether or not to have additional children. Factors that do not correlate with reproductive histories include knowledge of the genetic and metabolic nature of PKU, the relationship of PKU to mental retardation and special diet, parental upset about the diagnosis, sex of the affected child, parental IQ, religion, education, and social class. Correlations found related to the question, "Is PKU the reason you don't want more children?" include stress factors in family functioning, mother's upset with the diagnosis, father's concerns about being a carrier, sex of the child with PKU, and degree of knowledge about PKU. Many of the Collaborative Study clinics tend to be more concerned about the consequences of PKU on the family than on society, and feel that families should receive genetic counseling to determine their reproductive risks and future plans. Upon self-report, many clinics declare their counseling to be either "completely nondirective" or making a "conscious effort to be nondirective."     

Preliminary observations on polar body extrusion and pronuclear formation in human oocytes using time-lapse video cinematography

In this study, we have used time-lapse video cinematography to study fertilization in 50 human oocytes that had undergone intracytoplasmic sperm injection (ICSI). Time-lapse recording commenced shortly after ICSI and proceeded for 17-20 h. Oocytes were cultured in an environmental chamber which was maintained under standard culture conditions. Overall, 38 oocytes (76%) were fertilized normally, and the fertilization rate and embryo quality were not significantly different from 487 sibling oocytes cultured in a conventional incubator. Normal fertilization followed a defined course of events, although the timing of these events varied markedly between oocytes. In 35 of the 38 fertilized oocytes (92%), there were circular waves of granulation within the ooplasm which had a periodicity of 20-53 min. The sperm head decondensed during this granulation phase. The second polar body was then extruded, and this was followed by the central formation of the male pronucleus. The female pronucleus formed in the cytoplasm adjacent to the second polar body at the same time as, or slightly after, the male pronucleus, and was subsequently drawn towards the male pronucleus until the two abutted. Both pronuclei then increased in size, the nucleoli moved around within the pronuclei and some nucleoli coalesced. During pronuclear growth, the organelles contracted from the cortex towards the centre of the oocyte, leaving a clear cortical zone. The oocyte decreased in diameter from 112 to 106 microm (P < 0.0001) during the course of the observation period. The female pronucleus was significantly smaller in diameter than the male pronucleus (24.1 and 22.4 microm respectively, P = 0.008) and contained fewer nucleoli (4.2 and 7.0 respectively, P < 0.0001). After time-lapse recording, oocytes were cultured for 48 h prior to embryo transfer or cryopreservation. Embryo quality was related to fertilization events and periodicity of the cytoplasmic wave, and it was found that good quality embryos arose from oocytes that had more uniform timing from injection to pronuclear abuttal and tended to have a longer cytoplasmic wave. In conclusion, we have shown that time-lapse video cinematography is an excellent tool for studying fertilization and early embryo development, and have demonstrated that human fertilization comprises numerous complex dynamic events.