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Biomedical subjects

K D Peters

Publications and source records attributed to K D Peters.

5 recordsLinked to original sources
PubMed2005

Androgen dependence in hamsters: overdose, tolerance, and potential opioidergic mechanisms.

Anabolic steroids are drugs of abuse. However, the potential for steroid reward and addiction remains largely unexplored. This study used i.c.v. testosterone self-administration and controlled infusions of testosterone or vehicle in hamsters to explore central mechanisms of androgen overdose. Forty-two hamsters used nose-pokes to self-administer 1 microg/microl testosterone i.c.v. 4 h/day in an operant chamber. During 1-56 days of androgen self-administration, 10 (24%) hamsters died. Deaths correlated with peak daily intake of testosterone. Of the hamsters that self-administered a peak intake of <20 microg/day, there was 100% survival (10/10). Survival decreased to 86% (19/22) when daily testosterone intake peaked at 20-60 microg/day. Only 30% (three of 10) survived when daily testosterone intake exceeded 60 microg/day. Deaths are not due to volume or vehicle because i.c.v. infusions of 80 mul vehicle had no effect. Testosterone overdose resembles opiate intoxication. When male hamsters received infusions of 40 microg testosterone, locomotion (25.1+/-18.8 grid-crossings/10 min), respiration (72.7+/-5.4 breaths/min) and body temperature (33.5+/-0.4 degrees C) were significantly reduced, compared with males receiving vehicle infusions (186.1+/-8.1 crossings/10 min, 117.6+/-1.0 breaths/min, 35.9+/-0.1 degrees C, P<0.05). However, males developed tolerance to continued daily testosterone infusion. After 15 days, locomotion (170.2+/-6.3 crossings), respiration (118.4+/-1.3 breaths/min), and body temperature (35.3+/-0.3 degrees C) in testosterone-infused males were equivalent to that in vehicle controls (P>0.05). The depressive effects of testosterone infusion are blocked by the opioid antagonist, naltrexone. With naltrexone pre-treatment (10 mg/kg s.c.), locomotion (183.7+/-1.8 crossings/10 min), respiration (116.9+/-0.3 breaths/min), and body temperature (36.1+/-0.4 degrees C) during testosterone infusion were equivalent to vehicle controls. Likewise, naltrexone prevents the reinforcing effects of i.c.v. testosterone self-administration. These results indicate that testosterone at high doses causes central autonomic depression, which may be a factor in deaths during self-administration. As well, the depressive effects of large quantities of testosterone may be mediated, at least in part, by an opioidergic mechanism.

Anabolic Agents↗
PubMed1998

Deaths: final data for 1996.

OBJECTIVES: This report presents 1996 data on U.S. deaths and death rates according to demographic and medical characteristics such as age, sex, race, Hispanic origin, marital status, educational attainment, injury at work, State of residence, and cause of death. Trends and patterns in general mortality, life expectancy, and infant and maternal mortality are also described. METHODS: In 1996 a total of 2,314,690 deaths were reported in the United States. This report presents descriptive tabulations of information reported on the death certificates. Death certificates are completed by funeral directors, attending physicians, medical examiners, and coroners. Original records are filed in the state registration offices. Statistical information is compiled into a national data base through the Vital Statistics Cooperative Program of the National Center for Health Statistics, Centers for Disease Control and Prevention. Changes between 1995 and 1996 in death rates and differences in death rates across demographic groups in 1996 are tested for statistical significance. Unless otherwise specified reported differences are statistically significant. RESULTS: The 1996 age-adjusted death rate for the United States decreased, reaching an all-time low of 491.6 deaths per 100,000 standard population, and life expectancy at birth increased by 0.3 years to 76.1 years, a record high. The 15 leading causes of death remained the same as in 1995, although there were changes in the ranking of some causes. Replacing homicide, septicemia became the 12th leading cause of death, and Alzheimer's disease moved from the 14th to the 13th leading cause. For the third consecutive year, the number of homicide deaths dropped, making it the 14th leading cause of death. Mortality declined for all age groups, including persons aged 85 and over. The largest decline in age-adjusted death rates among the leading causes of death was for Human immunodeficiency virus infection, which dropped 28.8 percent in 1996, compared with the previous year. The infant mortality rate declined by 4 percent to a record low of 7.3 infant deaths per 1,000 live births in 1996. Neonatal and postneonatal mortality rates declined for all races combined as well as for postneonatal white infants. Although not statistically significant, mortality rates for white and black neonatal infants and black postneonatal infants also declined. CONCLUSIONS: The overall improvements in general mortality and life expectancy in 1996 continue the long-term downward trend in U.S. mortality. The drop in U.S. infant mortality continues the steady declines of the past four decades.

Adolescent↗
PubMed1998

Annual summary of vital statistics-1997.

Many positive trends in the health of Americans continued into 1997. In 1997, the preliminary birth rate declined slightly to 14.6 births per 1000 population, and the fertility rate, births per 1000 women 15 to 44 years of age, was unchanged from the previous year (65.3). These indicators suggest that the downward trend in births observed since the early 1990s may have abated. Fertility rates for white, black, and Native American women were essentially unchanged between 1996 and 1997. Fertility among Hispanic women declined 2% in 1997 to 103.1, the lowest level reported since national data for this group have been available. For the sixth consecutive year, birth rates dropped for teens. Birth rates for women 30 years or older continued to increase. The proportion of births to unmarried women (32.4%) was unchanged in 1997. The trend toward earlier utilization of prenatal care continued for 1997; 82.5% of women began prenatal care in the first trimester. There was no change in the percentage with late (third trimester) or no care in 1997. The cesarean delivery rate rose slightly to 20.8% in 1997, a reversal of the downward trend observed since 1989. The percentage of low birth weight (LBW) infants rose again in 1997 to 7.5%. The percentage of very low birth weight was up only slightly to 1.41%. Among births to white mothers, LBW increased for the fifth consecutive year, to 6.5%, whereas the rate for black mothers remained unchanged at 13%. Much, but not all, of the rise in LBW for white mothers during the 1990s can be attributed to an increase in multiple births. In 1996, the multiple birth rate rose again by 5%, and the higher-order multiple birth rate climbed by 20%. Infant mortality reached an all time low level of 7.1 deaths per 1000 births, based on preliminary 1997 data. Both neonatal and postneonatal mortality rates declined. In 1996, 64% of all infant deaths occurred to the 7.4% of infants born at LBW. Infant mortality rates continue to be more than two times greater for black than for white infants. Among all the states in 1996, Maine, Massachusetts, and New Hampshire had the lowest infant mortality rates. Despite declines in infant mortality, the United States continues to rank poorly in international comparisons of infant mortality. Expectation of life at birth reached a new high in 1997 of 76.5 years for all gender and race groups combined. Age-adjusted death rates declined in 1997 for diseases of the heart, accidents and adverse affects (unintentional injuries), homicide, suicide, malignant neoplasms, cerebrovascular disease, chronic liver disease and cirrhosis, and diabetes. In 1997, mortality due to HIV infection declined by 47%. Death rates for children from all major causes declined again in 1997. Motor vehicle traffic injuries and firearm injuries were the two major causes of traumatic death. A large proportion of childhood deaths continue to occur as a result of preventable injuries.

Adolescent↗
PubMed1997

Births and deaths: United States, 1996.

OBJECTIVES: This report presents preliminary data on births and deaths in the United States from the National Center for Health Statistics for 1996. U.S. data are shown by age, race, and Hispanic origin. National and State data on births by marital status, prenatal care, cesarean delivery, and low birthweight are also presented. Mortality data presented include life expectancy, leading causes of death, and infant mortality. METHODS: This report, the third in a new statistical series, presents preliminary data for 1996 on births and deaths based on a substantial sample of vital records. The records are weighted to independent control counts of births, infant deaths, and total deaths received in State vital statistics offices during calendar year 1996. RESULTS: According to preliminary data for 1996, the birth rate for teenagers dropped 4 percent in 1996 to 54.7 births per 1,000 women aged 15-19 years. The teen birth rate has declined 12 percent since 1991 (62.1), with larger reductions for young teenagers 15-17 years and for black teenagers. Birth rates for women aged 20-34 years increased 1-2 percent, while rates for women aged 35-44 years rose 3 percent. The number and percent of births to unmarried women increased about 1 percent, while the birth rate for unmarried women declined 1 percent. The rate of prenatal care utilization improved and the cesarean delivery rate declined. The overall low birthweight rate increased to 7.4 percent. The 1996 preliminary infant mortality rate reached a record low of 7.2 infant deaths per 1,000 live births with all-time lows for white and black infants. Life expectancy reached a record high of 76.1 years with all-time highs for white and black males and black females. The largest declines in age-adjusted death rates among the leading causes of death were for Human immunodeficiency virus (HIV) (26 percent) and Homicide (11 percent), which dropped from the 12th to the 14th leading cause of death.

Adolescent↗