Social cognition and subclinical paranoid ideation

OBJECTIVE

A number of cognitive biases have been identified relevant to persecutory thought (e.g. exaggerated self-serving bias). Moreover, findings of increased depressed mood in conjunction with high levels of self-esteem have contributed to theories of persecutory ideation (e.g. Bentall, Kinderman, Kaney, 1994). Using a nonclinical sample, the present study sought to expand upon previous research by examining the linear relationship between persecutory ideation and multiple clinical and social cognitive variables.

DESIGN

A cross-sectional design was used. Correlational and multiple regression analyses were conducted.

METHOD

One hundred and ninety-three undergraduate students were administered a battery of questionnaires which assessed the following domains: Paranoid ideation, depression, social anxiety, self-monitoring, attributional style and self-esteem.

RESULTS

Higher levels of paranoid ideation were significantly associated with greater depressed mood, social anxiety and avoidance, evaluation apprehension, self-monitoring and lower self-esteem. There were no significant associations between paranoid ideation and attributional biases.

CONCLUSIONS

These findings suggest that mood, anxiety and perceptions of the self are related to paranoid ideation in a nonclinical sample. These findings are tempered, however, by studying a nonclinical sample and the self-report measures of paranoid ideation that might be assessing multiple aspects of paranoid thought (e.g. ideas of reference).

Births: preliminary data for 2000

OBJECTIVES

This report presents preliminary data for 2000 on births in the United States. U.S. data on births are shown by age, race, and Hispanic origin of mother. Data on marital status, prenatal care, cesarean delivery, and low birthweight are also presented.

METHODS

Data in this report are based on more than 96 percent of births for 2000. The records are weighted to independent control counts of births received in State vital statistics offices in 2000. Comparisons are made with 1999 final data.

RESULTS

The number of births rose 3 percent between 1999 and 2000. The crude birth rate increased to 14.8 per 1,000 population in 2000, 2 percent higher than the 1999 rate. The fertility rate rose 3 percent to 67.6 per 1,000 women aged 15-44 years between 1999 and 2000. The birth rate for teenagers, which has been falling since 1991, declined 2 percent in 2000 to 48.7 births per 1,000 females aged 15-19 years, another historic low. The rate for teenagers 15-17 years fell 4 percent, and the rate for 18-19 year olds was down 1 percent. Since 1991, rates have fallen 29 percent for teenagers 15-17 years and 16 percent for teenagers 18-19 years. Birth rates for all of the older age groups increased for 1999-2000: 1 percent among women aged 20-24 years, 3 percent for women aged 25-29 years, and 5 percent for women in their thirties. Rates for women aged 40-54 years were also up for 2000. The birth rate for unmarried women increased 2 percent to 45.2 births per 1,000 unmarried women aged 15-44 years in 2000, but was still lower than the peak reached in 1994. The number of births to unmarried women was up 3 percent, the highest number ever reported in the United States. However, the number of births to unmarried teenagers declined. The proportion of women who began prenatal care in the first trimester of pregnancy (83.2 percent) did not improve for 2000, nor did the rate of low birthweight (7.6 percent). The total cesarean rate rose for the fourth consecutive year to 22.9 percent, the result of both a rise in the rate of primary cesarean deliveries and a decline in the rate of vaginal births after previous cesarean delivery.

Nucleoside analogues as highly potent and selective inhibitors of herpes simplex virus thymidine kinase

A series of carboxamide derivatives of 5'-amino-2',5'-dideoxy-5-ethyluridine has been prepared as inhibitors of HSV-TK (herpes simplex virus thymidine kinase). The most potent compounds were derived from xanthene, thioxanthene and dihydroanthracene carboxylic acids. The lead compounds show subnanomolar IC(50) values against HSV TKs.

A sensitive, single-tube assay to measure the enzymatic activities of influenza RNA polymerase and other poly(A) polymerases: application to kinetic and inhibitor analysis

We describe a fast and robust new assay format to measure poly(A) polymerase (PAP) activity in a microtiter plate format. The new assay principle uses only natural nucleotide triphosphates and avoids a labour-intensive filtration step. A coupled enzymatic system combining PAP and reverse transcriptase forms the basis of the assay. The PAP generates a poly(A) tail on a RNA substrate and the reverse transcriptase is used to quantify the polyadenylated RNA by extension of a biotinylated oligo-dT primer. We demonstrate the principle of the assay using influenza virus RNA polymerase and yeast PAP as examples. A specific increase in the K(m) value for ATP and the observation of burst kinetics in the polyadenylation dependent, but not in the polyadenylation independent, assay suggest that a rate limiting step of influenza polymerase activity occurs after transcription elongation. Yeast PAP was used to validate the assay as an example of a template independent PAP. The new yeast PAP assay was approximately 100-fold more sensitive than the conventional TCA precipitation assay for yeast PAP, but the kinetic analysis of the PAP reaction gave similar results in both assays. The two enzymes show important differences with respect to inhibition by 3'-deoxy-ATP. Whereas the K(i) value for 3'-deoxy-ATP (105-117 microM) is similar to the K(m) value for ATP (186 microM) in the case of influenza RNA polymerase, the K(i) value for 3'-deoxy-ATP (0.4-0.6 microM) is approximately 100-fold lower than the K(m) value for ATP (50 microM) in the case of yeast PAP.

On the duration of spatial fluency measures

Various measures of spatial fluency have been developed and have been shown to be sensitive to right frontal lobe dysfunction. Patients with diffuse cerebral injuries (traumatic brain injury) also show impaired performance. Administration times for these tests range from three to five minutes. It is well known that longer tests provide more reliable data. In the present study, the base rates of unique designs and perseverative errors on the Five-Point Test were examined minute-by-minute for ten minutes, in a sample of healthy young adults (n=80). Contrasts between each minute showed significant decreases in number of unique designs to the ninth minute (significant at p<.001). Contrasts between each minute revealed significant increases (significant at p<.00l) in percentage of perseverative errors to the eighth minute. Data demonstrating the progressive decrease of unique designs and progressive increase of perseverative errors as a function of time have important implications for clinical practice. Optimal administration time is considered in the context of clinicians' objectives.

Births: final data for 1999

OBJECTIVES

This report presents 1999 data on U.S. births according to a wide variety of characteristics. Data are presented for maternal demographic characteristics including age, live-birth order, race, Hispanic origin, marital status, and educational attainment; maternal characteristics (medical risk factors, weight gain, tobacco and alcohol use); medical care utilization by pregnant women (prenatal care, obstetric procedures, complications of labor and/or delivery, attendant at birth, and method of delivery); and infant characteristics (period of gestation, birthweight, Apgar score, abnormal conditions, congenital anomalies, and multiple births). Also presented are birth and fertility rates by age, live-birth order, race, Hispanic origin, and marital status. Selected data by mother's State of residence are shown, as well as data on month and day of birth, sex ratio, and age of father. Trends in fertility patterns and maternal and infant characteristics are described and interpreted.

METHODS

Descriptive tabulations of data reported on the birth certificates of the 3.96 million births that occurred in 1999 are presented.

RESULTS

Overall birth and fertility rates changed less than 1 percent in 1999. Teenage birth rates fell 2 to 6 percent. The rate for women aged 20-24 years declined slightly, while rates for women in their late twenties and their thirties rose 2 to 3 percent each. The number of births to unmarried women, the birth rate, and the percent of births that were to unmarried women each rose 1 percent or less. Smoking by pregnant women overall dropped again, but rose among women aged 18-24 years. Improvements in prenatal care utilization continued. The cesarean delivery rate increased for the third year after declining for 7 consecutive years. The proportion of multiple births continued to rise; however, higher order multiple births (e.g., triplets, quadruplets) declined for the first time in over a decade, following increases of 13 percent per year during 1990-98. The percent low birthweight remained at 7.6 percent, while preterm births rose to 11.8 percent. These trends are in large part the result of increases in multiple births.

Telomere erosion and senescence in human articular cartilage chondrocytes

Aging and the degeneration of articular cartilage in osteoarthritis are distinct processes, but a strong association exists between age and the incidence and prevalence of osteoarthritis. We hypothesized that this association is due to in vivo replicative senescence, which causes age-related declines in the ability of chondrocytes to maintain articular cartilage. For this hypothesis to be tested, senescence-associated markers were measured in human articular chondrocytes from donors ranging in age from 1 to 87 years. These measures included in situ staining for senescence-associated beta-galactosidase activity, (3)H-thymidine incorporation assays for mitotic activity, and Southern blots for telomere length determinations. We found that senescence-associated beta-galactosidase activity increased with age, whereas both mitotic activity and mean telomere length declined. These findings indicate that chondrocyte replicative senescence occurs in vivo and support the hypothesis that the association between osteoarthritis and aging is due in part to replicative senescence. The data also imply that transplantation procedures performed to restore damaged articular surfaces could be limited by the inability of older chondrocytes to form new cartilage after transplantation.

Astrocytes degenerate in frontotemporal dementia: possible relation to hypoperfusion

To understand the extent and specificity of astrocyte pathology in sporadic frontotemporal dementia (FTD), we examined several FTD cases for molecular and morphologic characteristics of astrocyte degeneration. We quantified reactive and degenerating astrocytes in sections of frontal, temporal, parietal, and occipital cortex identified using glial fibrillary acidic protein (GFAP) immunoreactivity, terminal deoxynucleotidyl transferase (TdT) labeling, and morphological characteristics and compared them with nondemented, age-matched control brains. Conventional and confocal microscopy revealed that a subpopulation of GFAP(+) astrocytes exhibited positive TdT labeling and beading of their processes in the frontal, temporal, and parietal cortices in 5 of 7 FTD cases that also exhibited gliosis. This morphology was reproduced in cultured astrocytes using ischemic insults. Degenerating astrocytes in FTD correlated inversely with cerebral blood flow as measured by single photon emission computed tomography (SPECT) analysis of (133)Xe inhalation (r = 0.55, p < 0.05). Furthermore, areas of significant astrogliosis corresponded to areas of SPECT hypoperfusion, suggesting that astrocytes may be affected by or perhaps have a causal role in the disturbances of cerebral perfusion in FTD.

Identification of adult populations at high risk for dental caries using a computerized database and patient records: a pilot project

OBJECTIVES

The purpose of this study is to test the usefulness of dental insurance claims history, supplemented with radiographic caries diagnoses, as a means of identifying caries-active and caries-inactive working adults, as determined by bacterial levels. Computerized identification of at-risk groups may facilitate subject selection for clinical trials designed to test caries-preventive strategies.

METHODS

Two groups of subjects were initially selected from an insurance database based upon their dental service utilization during a one-year period: a "low restorative" group of individuals defined as persons who had received no restorative treatment, and a "high restorative" group comprised of individuals who had received at least three multisurfaced restorations. A chart review confirmed a diagnosis of caries in the high restorative group and an absence of caries in the low restorative group. Subjects were then approached for saliva collection. The low and high restorative groups were compared for salivary mutans streptococci and lactobacilli levels, stimulated flow rate, and buffer capacity (n = 48).

RESULTS

The high and low restorative groups differed in mutans streptococci levels, but not on other measures.

CONCLUSIONS

A group of subjects who had recently received multisurfaced restorations that were placed for reasons of caries had significantly higher levels of mutans streptococci and potential for continued caries activity when compared to a group of subjects who had received no restorations and were caries free.

The prevalence and correlates of psychological distress following physical and sexual assault in a young adult cohort

Among a birth cohort of New Zealand's 21-year-olds, 41% experienced physical or sexual assault in the previous 12 months. The level of psychological distress experienced by the 374 victims was determined in interviews assessing for symptoms indicative of posttraumatic stress disorder and ratings of impairment in activities of daily living. Of the 141 women victims, 32.6% were identified as experiencing psychological distress as were 9.9% of the 233 men. For men, bivariate analyses showed psychological distress was significantly associated with factors indicative of increased assault severity, and for women an increased likelihood of distress was associated with the location of assault and the relationship to the assailant. Positive indicators of social support were not significantly associated with less adverse psychological outcomes. However, for both men and women, resisting the assailant was associated with a reduced likelihood of psychological distress. Multivariate analyses revealed that for both women and men, unemployment uniquely predicted variance in distress, over and above that accounted for by characteristics of the assault.

Paracetamol (acetaminophen) hypersensitivity

BACKGROUND

Acetaminophen (paracetamol) is an analgesic antipyretic drug with no antiinflammatory effects and is widely used worldwide. Earlier clinical studies reported IgE-mediated adverse reactions to acetaminophen, but in vivo and in vitro tests have been inconclusive.

OBJECTIVE

We propose to demonstrate an IgE-mediated mechanism in four patients with adverse reactions to acetaminophen (paracetamol). Tolerance to aspirin and other nonsteroidal antiinflammatory drugs are present in all patients.

METHODS

We studied four patients with anaphylactic reactions to acetaminophen who tolerated aspirin and other nonsteroidal antiinflammatory drugs. Skin tests, oral challenges and immunoassay for allergen-specific IgE antibodies with acetaminophen were performed in all patients.

RESULTS

All patients tolerated the aspirin oral challenge without adverse effects. In contrast, the oral challenge with acetaminophen produced adverse effects in all patients. Skin tests with acetaminophen were positive in two patients (3-mm wheal and flare) and IgE antibodies acetaminophen were detected in serum from two patients.

CONCLUSION

We describe four patients with adverse reactions to acetaminophen but with tolerance to aspirin and other nonsteroidal antiinflammatory drugs. Skin tests, oral challenges, and serum IgE results with acetaminophen suggest that an IgE-mediated mechanism is responsible for these reactions.

An internal histidine residue from the bacterial surface protein, PAM, mediates its binding to the kringle-2 domain of human plasminogen

The determinants of binding of a peptide lacking C-termini-exposed lysine residues to a kringle domain were investigated using an up-regulated lysine binding kringle (K2Pg[C4G/E56D/K72Y]) of plasminogen and a peptide (a1-PAM) with a sequence derived from a surface-exposed M-like streptococcal protein. Significant kringle-induced chemical shifts in a His side-chain of a1-PAM were revealed by two-dimensional NMR. Further studies using isothermal titration calorimetry (ITC) provided support for the involvement of His12 in the peptide/ protein complex. In an effort to screen a1-PAM-derived truncation peptides, a combinatorial mixture, a1deltaa2-PAM[H12X] (where X=Pro, Arg, His, Trp, Lys, Ala, Phe, Asp and Gly), was analyzed using the surface-enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI) platform. The major peptide that remained bound to the surface of the K2Pg[C4G/ E56D/K72Y]-containing chip was that containing His12, corresponding to the wild-type sequence. Minor peaks, representing binding, were obtained for Lys12-, Arg12- and Trp12-containing peptides. Individual peptides containing these amino acids were then examined using ITC and the binding constants obtained correlated with the relative strengths of binding estimated from the SELDI-based screen.

The role of chondrocyte-matrix interactions in maintaining and repairing articular cartilage

Throughout life chondrocytes maintain the articular cartilage matrix by replacing degraded macromolecules and respond to focal cartilage injury or degeneration by increasing local synthesis activity. These observations suggest that mechanisms exist within articular cartilage that stimulate chondrocyte anabolic activity in response to matrix degradation or damage. An important cartilage anabolic factor, insulin-like growth factor I (IGF-I), appears to have a role in stimulating chondrocyte anabolic activity. Although IGF-I is ubiquitous, its bioavailability is controlled by a class of secreted proteins, IGF binding proteins (IGFPBs). Of the six known IGFPBs, IGFBP-3 is the most abundant in human articular cartilage. We recently found that with increasing age, articular chondrocytes increase their expression of IGFBP-3. This observation led us to investigate the potential role of IGFBP-3 in chondrocyte-matrix interactions. Using immunofluorescent staining and confocal microscopy we found that IGFBP-3 accumulates with increasing age in the chondrocyte territorial matrix where it co-localizes with fibronectin, but not with tenascin-C or type VI collagen. Using purified proteins we demonstrated that IGFBP-3 binds to fibronectin in a dose dependent manner, but not to tenascin-C. In vitro studies showed that IGFBP-3 alone inhibited chondrocyte synthetic activity while intact fibronectin alone significantly stimulated activity. When fibronectin and IGFBP-3 were combined we found that the inhibitory activity of low concentrations of IGFPB-3 was enhanced. These observations indicate that in mature articular cartilage IGF-I is stored in the chondrocyte territorial matrix through binding to a complex of IGFPB-3 and intact fibronectin. Storage of IGF-I of the territorial matrix may help maintain a relatively constant level of available IGF-I and the local increase in matrix synthesis following matrix damage may result from release of IGF-I. This mechanism may have an important role in maintaining and repairing articular cartilage and failure of this mechanism may lead to progressive articular cartilage degeneration.

Births: preliminary data for 1999

OBJECTIVES

This report presents preliminary data for 1999 on births in the United States. U.S. data on births are shown by age, race, and Hispanic origin of mother. Data on marital status, prenatal care, cesarean delivery, and low birthweight are also presented.

METHODS

Data in this report are based on more than a 97-percent sample of births for 1999. The records are weighted to independent control counts of births received in State vital statistics offices in 1999. Comparisons are made with 1998 final data.

RESULTS

The crude birth rate in 1999 was 14.5 per 1,000 population, a slight decline from 1998 (14.6), returning to the level observed in 1997. However, the fertility rate, which is limited to women aged 15-44 years, was 65.8 in 1999, a slight increase over the rate for 1998 (65.6). The birth rate for teenagers continued to decline for 1998-99, dropping 3 percent to 49.6 births per 1,000 females aged 15-19 years. The 1999 rate for teenagers is 20 percent lower than the recent high point in 1991. The rate for young teenagers 15-17 years fell 6 percent, and the rate for teenagers 18-19 years declined 2 percent. Since 1991, rates have fallen 26 percent for teenagers 15-17 years, and 15 percent for teenagers 18-19 years. Birth rates for women aged 20-24 years declined slightly between 1998 and 1999 whereas the rate for women aged 25-29 years rose 2 percent. Birth rates for women in their thirties and forties continued their long increase. Rates for women in their thirties increased 2 to 3 percent and were the highest in three decades. The birth rate for women aged 40-44 years was the highest level reported since 1970. The birth rate for unmarried women in 1999 was 43.9 per 1,000, 1 percent lower than in 1998 and 6 percent lower than the peak level reported for 1994 (46.9). However, the number of births to unmarried women was up about 1 percent due to the continued increase in the number of unmarried women of childbearing age. The rate of prenatal care utilization continued to improve. The total cesarean rate increased 4 percent between 1998 and 1999 and continued a 3-year rise. The low birthweight rate remained unchanged at 7.6 percent.

Trends in twin birth outcomes and prenatal care utilization in the United States, 1981-1997

CONTEXT

Multiple births account for an increasing percentage of all low-birth-weight infants, preterm births, and infant mortality in the United States. Since 1981, the percentage of women with multiple births who received intensive prenatal care (defined as a high number of visits, exceeding the recommendation of the American College of Obstetricians and Gynecologists by approximately 1 SD beyond the mean number of visits for women initiating care within each trimester) has increased significantly.

OBJECTIVES

To explore the hypothesis that more aggressive management of twin-birth pregnancies may be associated with changes in birth outcomes in this population.

DESIGN, SETTING, AND SUBJECTS

Cross-sectional and trend analysis of data from the National Center for Health Statistics' birth and infant death records for all twin births occurring in the United States between 1981 and 1997, excluding those with missing or inconsistent data.

MAIN OUTCOME MEASURES

Trends in preterm birth, low birth weight, preterm and term small-for-gestational-age (SGA) births, and infant mortality, by level of prenatal care utilization.

RESULTS

The preterm birth rate for twins increased from 40.9% in 1981 to 55.0% in 1997. The percentage of low-birth-weight infants increased from 51.0% to 54.0%. The preterm SGA rate also increased from 11.9% to 14.1%, while the term SGA rate decreased from 30.7% to 20.5%. For women with intensive prenatal care utilization, the preterm birth rate increased from 35.1% to 55.8%, compared with an increase from 50.6% to 59.2% among women with only adequate use. Twin preterm deliveries involving either induction or first cesarean delivery also increased from 21.9% to 27.3% between 1989-1991 and 1995-1997. The twin infant mortality rate for women with intensive prenatal care use declined between 1983 and 1996 and remained lower than the overall twin infant mortality rate.

CONCLUSIONS

An apparent increase in medical interventions in the management of twins may result in the seeming incongruity of more prenatal care and more preterm births; however, these data suggest that women with intensive prenatal care utilization also have a lower infant mortality rate. JAMA. 2000;283:335-341

Tenascin-C in tendon regions subjected to compression

Tendon regions subjected almost exclusively to tension differ from regions subjected to high levels of compression as well as tension. Regions not exposed to compression consist primarily of spindle-shaped fibroblasts surrounded by densely packed longitudinally oriented collagen fibrils formed principally from type-I collagen. In contrast, regions subjected to compression have a fibrocartilagenous structure and composition: they consist of spherical cells surrounded by a matrix containing hyaline cartilage proteoglycans (aggrecan) and type-II collagen as well as type-I collagen. Reducing their adhesion to the matrix may help cells in the latter regions establish and maintain a spherical shape and minimize their deformation when the tissue is subjected to mechanical stress. We hypothesized that expression of tenascin-C, an anti-adhesive protein, is part of the adaptation of tendon cells to compression that helps establish and maintain fibrocartilagenous regions. To test this hypothesis, we compared segments of bovine flexor tendons subjected to repetitive compression (distal) with segments that are not subjected to compression (proximal) to determine whether they differed in tenascin-C content and expression. RNA and protein analyses showed that tenascin-C expression was elevated in the distal tendon. Tendon cells from the distal segment expressed more tenascin-C mRNA than did cells from the proximal segments for as long as 4 days in cell culture, indicating that increased tenascin-C expression is a relatively stable feature of the distal cells. Moreover, purified tenascin-C inhibited the attachment of cultured tendon cells to fibronectin. These observations support the hypothesis that tenascin-C expression is a cellular adaptation to compression that helps establish and maintain fibrocartilagenous regions of tendons by decreasing cell-matrix adhesion.

Reversible suppression of in vitro biomineralization by activation of protein kinase A

Parathyroid hormone (PTH-(1-34)) potently suppresses apatite deposition in osteoblastic cultures. These inhibitory effects are mediated through signaling events following PTH receptor binding. Using both selective inhibitors and activators of protein kinase A (PKA), this study shows that a transient activation of PKA is sufficient to account for PTH's inhibition of apatite deposition. This inhibition is not a result of reduced cell proliferation, reduced alkaline phosphatase activity, increased collagenase production, or lowering medium pH. Rather, data suggest a functional relationship between matrix assembly and apatite deposition in vitro. Bone sialoprotein (BSP) and apatite co-localize in the extracellular matrix of mineralizing cultures, with matrix deposition of BSP temporally preceding that of apatite. Transient activation of PKA by either PTH-(1-34) or short term cAMP analog treatment blocks the deposition of BSP in the extracellular matrix without a significant reduction in the total amount of BSP synthesized and secreted. This effect is reversible after allowing the cultures to recover in the absence of PKA activators for several days. Thus, a transient activation of PKA may suppress mineral deposition in vitro as a consequence of altering the assembly of an extracellular matrix permissive for apatite formation.

Births: final data for 1998

OBJECTIVES

This report presents 1998 data on U.S. births according to a wide variety of characteristics. Data are presented for maternal demographic characteristics including age, live-birth order, race, Hispanic origin, marital status, and educational attainment; maternal lifestyle and health characteristics (medical risk factors, weight gain, and tobacco and alcohol use); medical care utilization by pregnant women (prenatal care, obstetric procedures, complications of labor and/or delivery, attendant at birth, and method of delivery); and infant health characteristics (period of gestation, birthweight, Apgar score, abnormal conditions, congenital anomalies, and multiple births). Also presented are birth and fertility rates by age, live-birth order, race, Hispanic origin, and marital status. Selected data by mother's State of residence are shown including teenage birth rates and total fertility rates, as well as data on month and day of birth, sex ratio, and age of father. Trends in fertility patterns and maternal and infant characteristics are described and interpreted.

METHODS

Descriptive tabulations of data reported on the birth certificates of the 3.94 million births that occurred in 1998 are presented.

RESULTS

Birth and fertility rates increased in 1998 by about 1 percent, the first increase since 1990. Birth rates for teenagers fell 2-5 percent. Rates for women in their twenties increased 1-2 percent each, whereas rates for women in their thirties rose 2-4 percent. All measures of childbearing by unmarried women increased in 1998; the number of births rose 3 percent, the birth rate increased about 1 percent while the percent of births that were to unmarried women rose to 32.8 percent. Smoking by pregnant women overall dropped again in 1998, but continued to increase among teenagers. Improvements in prenatal care utilization continued. The cesarean delivery rate increased for the second year after declining for 7 consecutive years. The proportion of multiple births continued to rise; higher order multiple births (e.g., triplets, quadruplets) rose by 13 percent in 1998, following a 14 percent rise from 1996 to 1997. Key measures of birth outcome--the percents of low birthweight and preterm births--increased. These changes are in large part the result of increases in multiple births.

Damage control mechanisms in articular cartilage: the role of the insulin-like growth factor I axis

Articular chondrocytes maintain cartilage throughout life by replacing lost or damaged matrix with freshly synthesized material. Synthesis activity is regulated, rapidly increasing to well above basal levels in response to cartilage injury. Such responses suggest that synthesis activity is linked to the rate of matrix loss by endogenous "damage control" mechanisms. As a major stimulator of matrix synthesis in cartilage, insulin-like growth factor I (IGF-I) is likely to play a role in such mechanisms. Although IGF-I is nearly ubiquitous, its bioavailability in cartilage is controlled by IGF-I binding proteins (IGFBPs) secreted by chondrocytes. IGFBPs are part of a complex system, termed the IGF-I axis, that tightly regulates IGF-I activities. For the most part, IGFBPs block IGF-I activity by sequestering IGF-I from its cell surface receptor. We recently found that the expression of one binding protein, IGFBP-3, increases with chondrocyte age, paralleling an age-related decline in synthesis activity. In addition, IGFBP-3 is overexpressed in osteoarthritic cartilage, leading to metabolic disturbances that contribute to cartilage degeneration. These observations indicate that IGFBP-3 plays a crucial role in regulating matrix synthesis in cartilage, and suggest that cartilage damage control mechanisms may fail due to age-related changes in IGFBP-3 expression or distribution. Our investigation of this hypothesis began with immunolocalization studies to determine the tissue distribution of IGFBP-3 in human cartilage. We found that IGFBP-3 accumulated around chondrocytes in the pericellular/territorial matrix, where it co-localized with fibronectin, but not with the other matrix proteins tenascin-C and type VI collagen. This result suggested that the IGFBP-3 distribution is determined by binding to fibronectin. Binding studies using purified proteins demonstrated that IGFBP-3 does in fact bind to fibronectin, but not to tenascin-C or type VI collagen. Finally, we investigated the metabolic effects of fibronectin and IGFBP-3 in a chondrocyte culture system. These experiments showed that fibronectin enhanced the inhibitory effect that low concentrations of IGFBP-3 had on matrix synthesis. Taken together, these observations confirm that IGFBP-3-fibronectin interactions affect the IGF-I axis, and they indicate that IGF-I is stored in the chondrocyte territorial matrix through binding to a complex of IGFBP-3 and intact fibronectin. This arrangement may play an important role in cartilage damage control mechanisms. The local increase in matrix synthesis following injury could result from damage-induced IGF-I release from such pools. An age-related failure to organize this system may contribute to degenerative disease.

Annual summary of vital statistics--1998

Most vital statistics indicators of the health of Americans were stable or showed modest improvements between 1997 and 1998. The preliminary birth rate in 1998 was 14.6 births per 1000 population, up slightly from the record low reported for 1997 (14.5). The fertility rate, births per 1000 women aged 15 to 44 years, increased 1% to 65.6 in 1998, compared with 65.0 in 1997. The 1998 increases, although modest, were the first since 1990, halting the steady decline in the number of births and birth and fertility rates in the 1990s. Fertility rates for total white, non-Hispanic white, and Native American women each increased from 1% to 2% in 1998. The fertility rate for black women declined 19% from 1990 to 1996, but has changed little since 1996. The rate for Hispanic women, which dropped 2%, was lower than in any year for which national data have been available. Birth rates for women 30 years or older continued to increase. The proportion of births to unmarried women remained about the same at one third. The birth rate for teen mothers declined again for the seventh consecutive year, and the use of timely prenatal care (82.8%) improved for the ninth consecutive year, especially for black (73.3%) and Hispanic (74.3%) mothers. The number and rate of multiple births continued their dramatic rise; the number of triplet and higher-order multiple births jumped 16% between 1996 and 1997, accounting, in part, for the slight increase in the percentage of low birth weight (LBW) births. LBW continued to increase from 1997 to 1998 to 7.6%. The infant mortality rate (IMR) was unchanged from 1997 to 1998 (7.2 per 1000 live births). The ratio of the IMR among black infants to that for white infants (2.4) remained the same in 1998 as in 1997. Racial differences in infant mortality remain a major public health concern. In 1997, 65% of all infant deaths occurred to the 7.5% of infants born LBW. Among all of the states, Maine, Massachusetts, and New Hampshire had the lowest IMRs. State-by-state differences in IMR reflect racial composition, the percentage LBW, and birth weight-specific neonatal mortality rate for each state. The United States continues to rank poorly in international comparisons of infant mortality. Expectation of life at birth increased slightly to 76.7 years for all gender and race groups combined. Death rates in the United States continue to decline, including a drop in mortality from human immunodeficiency virus. The age-adjusted death rate for suicide declined 6% in 1998; homicide declined 14%. Death rates for children from all major causes declined again in 1998. A large proportion of childhood deaths, however, continue to occur as a result of preventable injuries.