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PubMed1990

Dietary restriction and aging: the initiation of a primate study.

Juvenile (1 yr) and adult (3-5 yr) male rhesus monkeys (Macaca mulatta) and juvenile (1-4 yr) and adult (5-10 yr) male squirrel monkeys (Saimiri sciureus) were fed a diet at or near ad libitum levels based on recommended caloric intake for age and body weight or fed 30% less of the same diet with this restriction gradually introduced over a 3-mo period. Analysis of body weights among these respective control and experimental groups from the first year of the study indicated that the monkeys undergoing dietary restriction were gaining weight at a markedly slower rate compared to control values. Actual food intake among diet-restricted groups had been reduced 22-24% below control levels. Periodic analysis of hematology and blood chemistry measurements over the first year of the study detected few significant differences between control and experimental groups to indicate that diet restriction was not detrimental to general health. When values obtained from hematology and blood chemistry measurements of juvenile and adult groups (control and experimental groups combined) were compared to ad libitum fed old monkeys from each species (greater than 18 yr for rhesus; greater than 10 yr for squirrel monkeys), many significant age differences were noted. Among the largest and most consistent findings in both species were age-related decreases in concentrations of lymphocytes, serum glutamic oxalacetic transaminase, serum glutamic pyruvic transaminase, alkaline phosphatase, and phosphates as well as the albumin/globulin ratio and the blood urea nitrogen/creatinine ratio. Age-related increases in serum globulin and creatinine concentrations were also found. These parameters as well as many others being implemented in the study will be monitored further to determine if diet restriction affects the rate of development as well as aging as observed in numerous rodent studies applying such nutritional manipulations.

Aging↗
PubMed2006

Do testicular seminoma and nonseminoma share the same etiology? Evidence from an age-period-cohort analysis of incidence trends in eight European countries.

The incidence of the two main clinical subentities of testicular germ cell cancer (seminoma and nonseminoma) is increasing throughout Europe. Most studies have revealed little variation in risk factors between the two subtypes. This study compared generation-specific trends in eight European countries, hypothesizing that similar temporal pattern by birth cohort implied that seminoma and nonseminoma had a largely comparable etiology. The results are presented using the age-period-cohort model and the nonidentifiability problem highlighted by partitioning the age, period, and cohort effects in terms of their linear and curvature component parts, assuming a priori that cohort effects predominated. Despite uniform overall increases by calendar period, declining rates of nonseminoma but not pure seminoma were observed in the majority of countries during the 1990s. The subtype trends were, however, largely analogous on a birth cohort scale. Notable observations were a decline in rates of both subtypes among recent birth cohorts in Switzerland and a short-term wartime effect in several countries, involving an attenuation of increasing risk of both subtypes in men born in 1940 to 1945. Departures from the steady increases in testicular cancer over time were likely to occur for nonseminomas some years ahead of seminoma on a period scale. The importance of birth cohort coincided with the view that given a short time interval of susceptibility to exposures earlier in life and a biologically constant time to diagnosis, all temporal changes in rate-limiting exposures should appear as generational effects. Trends in seminoma and nonseminoma conform to largely the same temporal patterns on this scale, implying that they share important etiologic factors.

Adolescent↗
PubMed2002

Trends in breast cancer incidence in Hong Kong between 1973 and 1999: an age-period-cohort analysis.

Hong Kong has the highest breast cancer incidence in Asia and studying secular changes in its rates may lead to hypotheses regarding disease aetiology and also predictions of future trends for China. We examined statistics from the Hong Kong Cancer Registry based on 26 566 cases of invasive breast cancer from 1973 to 1999. The trends in breast cancer incidence were studied using log-linear longitudinal models. We further analysed the independent effects of chronological age, time period and birth cohort on incidence trends using age-period-cohort modelling. The average annual per cent change of the age-standardised incidence was 3.6% during 1973-1999. Age-period-cohort modelling indicated the incidence development was predominantly a cohort effect, where the rise in relative risk was seemingly linear in successive birth cohorts, showing a 2-3-fold difference when comparing women born in the 1960's with those born around 1900. Our results suggest that direct and indirect consequences of westernisation may have been responsible for most of the observed increase in breast cancer incidence. As China moves towards a more westernised way of life, we can expect an emerging epidemic of breast cancer as Hong Kong's experience has demonstrated.

Adult↗
PubMed2004

Age-period-cohort analysis of the Bovine Spongiform Encephalopathy (BSE) epidemic in Switzerland.

Cattle born after animal-feed control measures were implemented in 1990 have become BSE cases in Switzerland, indicating sub-optimal effectiveness of these measures. To evaluate these measures, the incidence of BSE cases in Switzerland recorded through clinical case reporting from January 1991 to June 2000 (categorized into age groups and birth cohorts of 6-month duration) was analyzed by Poisson log-linear regression using an age-period-cohort model. The incidence was maximum in the cattle cohort born from October 1989 to March 1990, and dropped to zero in the cohort born from April to September 1991. A second peak was observed in a cohort born from April to September 1994. The first drop of incidence is interpreted as a result of initial implementation of the feed ban in 1990. The second peak might be related to exposure of cattle to feed intended for pigs and poultry.

Animal Feed↗
PubMed2001

Age period cohort analysis of time trends in regional mortality rates in England, Wales and Scotland.

Previous studies have demonstrated regional variation in mortality rates, this reducing for younger but not older individuals. However, it has not been clear from such studies whether or not the overall findings can or cannot be attributed to particular regions that may have abnormal patterns of change over time. We analyse mortality rates by region using data from the census years from 1931 until 1991 for adults. Age period cohort models, based on the local 'curvatures', are used to describe the changes in the rates. We also use estimable contrasts to compare the later periods with the earlier periods and to compare pre- and post-war cohorts. There is strong evidence that the changes in the mortality rates are associated with non-linear period and cohort effects. There is no evidence that these curvatures vary over regions. There is evidence that the curvatures are not the same among men and women. Among women there is evidence that there is a change in trend in the periods from 1961 to 1991 compared with the trend in the earlier periods from 1931 to 1951, such that the reduction in the mortality rates with time are slowing down for women. Among men who had higher mortality rates, there is not so much evidence of a slowing down of the reduction. Post-war cohorts of women from 1941 onwards are enjoying a reduction in mortality compared with the cohorts from 1901 to 31, while among men there is no evidence of a change in mortality trends among younger cohorts. Changes in the mortality rates over regions have come about from different long-term temporal trends in the regions rather than abrupt changes taking place at different times in different regions. The general convergence of mortality rates over regions over time with a consequent reduction in regional variance is masked by two regions, Scotland and East Anglia. These regions appear to differ from the regions as a whole in the relationship of mortality to age at a given period and in the reduction of mortality over time (drift), Scotland having a higher mortality, especially at younger ages, and lower downward trend, and East Anglia vice versa.

Adolescent↗
PubMed2004

Cerebral microdialysis of patients with severe traumatic brain injury exhibits highly individualistic patterns as visualized by cluster analysis with self-organizing maps.

OBJECTIVE: To analyze patterns of cerebral microdialysis in patients with traumatic brain injury and, with a neural network methodology, investigate pattern relationships to intracranial pressure and cerebral perfusion pressure. DESIGN: Retrospective. SETTING: University hospital, adult neurosurgical intensive care unit. PATIENTS: Twenty-six patients with severe traumatic brain injury. All consecutive traumatic brain injured patients (Glasgow Coma Scale < or =8) with microdialysis monitoring, analyzing glutamate, lactate, pyruvate, and glucose in both penumbral and nonpenumbral tissue. INTERVENTIONS: None; patients received the unit's standard neurointensive care procedure. MEASUREMENTS AND MAIN RESULTS: We used 2084 hrs of complete microdialysis data sets (eight markers) to train Kohonen self-organizing maps. The self-organizing map algorithm is a data-clustering method that reduces high-dimensional information to a two-dimensional representation on a grid (map), retaining local relationships in the data. Maps were colored (overlaid) for intracranial pressure, cerebral perfusion pressure, and outcome, to explore relationships with underlying microdialysis patterns. The maps exhibited a striking clustering of patients, with unique microdialysis patterns that were recognizable throughout the analysis period. This also held true for most microdialysis patterns characteristic of ischemia. These patients with ischemic patterns can have good outcomes, suggesting a disparity between microdialysis values and severity of traumatic brain injury. CONCLUSION: Using an artificial neural network-like clustering technique, Kohonen self-organizing maps, we have shown that cerebral microdialysis, in traumatic brain injury, exhibits strikingly individualistic patterns that are identifiable throughout the analysis period. Because patients form their own clusters, microdialysis patterns, during periods of increased intracranial pressure or decreased cerebral perfusion pressure, will be found within these clusters. Consequently, no common pattern of microdialysis can be seen among patients within the range of our data. We suggest that these individualistic patterns reflect not only metabolic states of traumatic brain injury but also local gradients seen with small volume sampling. Future investigation should focus on relating these patterns, and movement within and from clusters, to metabolic states of the complex pathophysiology of traumatic brain injury.

Adolescent↗
PubMed1985

Circadian variation in mitotic influx in a keratinized epithelium. The stathmokinetic technique used in vivo on the hamster cheek pouch epithelium and analyzed by periodic regression analysis.

An in vivo study of the hamster cheek pouch epithelium using the stathmokinetic technique (Colcemid) demonstrated a circadian variation in mitotic influx. Based on measurements of all nucleated epithelial cells the diurnal mean was estimated in two separate experiments as 0.34%/h +/- 0.02 (SE) and 0.27%/h +/- 0.02 (SE) respectively. 3HTdR was injected in the latter study (a double labelling experiment). The significant difference between the two experiments is, however, probably due to biological variations. The maximal values for the mitotic rate were found during the light (resting) period, as were the maximal values for the mitotic index. The mean mitotic influx for the 'light period' was estimated as 0.5-0.4%/h, and for the 'dark period' as 0.2%/h. Independent analyses demonstrated the necessity of a circadian-dependent correction of the 1 and 4 h values of accumulated metaphases. The 1 h value was significantly too high during the light as well as the dark period. The 4 h value was found to be too low, but only significantly so during the dark period. Basing the estimation of mitotic rate on the 3 h accumulation value produced only very similar results to those found by using all four accumulation periods. The use of overlapping experiments proved that only cells entering mitosis after Colcemid application were arrested, so that when arrested metaphases were counted the accumulation line was correctly drawn through the origin. In the latter study (the double labelling experiment) both S- (Møller and Keiding 1982) and mitotic influx were estimated, the estimates being 0.55%/h +/- 0.03 (SE) and 0.27%/h +/- 0.02 (SE) respectively. Even considering possible methodological problems, the discrepancy between the S efflux and the mitotic influx indicates cell death and/or differentiation from G2.

Anaphase↗
PubMed1997

The US orphan drug programme 1983-1995.

The Orphan Drug Act has become a staple of food and drug law in the US. The experience with the US programme continues to serve as a useful reference point as interest in orphan drug incentive programmes expands globally. This article first reviews details of the legislation and orphan drug regulations, and then provides a 13-year overview (1983-1995) of orphan drug activity in the US, including descriptive data on the designated and approved orphan drugs, their indications and sponsors. In light of a recent challenge to the Food and Drug Administration's (FDA's) authority under the Act, we also examine the interplay between the exclusivity provision of the Act and the orphan drug regulations that define when 2 drugs will be considered the 'same' for the purposes of the Act. A recent court decision affirming the FDA's interpretation of the clinical superiority provisions of the regulations suggests that orphan exclusivity may be less predictable and less certain than it has been in the past. Finally, we consider the usefulness to orphan drug sponsors of other initiatives such as FDA's early access and fast-track approval programmes, and the extent to which the FDA's discretion to waive, defer and reduce prescription drug user fees has worked to the benefit of orphan drug sponsors. Over the 13-year analysis period, the FDA granted 631 orphan designations involving 450 different drugs, for which 121 FDA marketing approvals have been granted. Those with both treatment investigational drug designation and fast-track approval status appeared to benefit substantially from shorter development times. The indications targeted by the orphan drugs fall into 8 categories, with 40% of all orphan indications involving cancer and genetic diseases. Evident in the latter part of the analysis period is the increasing share of orphan activity attributable to biotechnology firms. Even though the Prescription Drug User Fee Act of 1992 did not recognise orphan status for the purpose of waiving or reducing the amount of fees payable, almost one-third (32%) of the $US 8,531,550 in user fee revenue foregone through waivers and reductions was attributable to orphan drugs.

Drug Approval↗
PubMed2002

Stability of active systems with a spatially periodic activity: Analysis of a simple model and application to the boiling crisis problem.

We investigate theoretically the possibility to control the transition between two metastable states in reactive systems by imposing a spatial modulation. In particular, we consider the technologically very important case of the transition between the low temperature (nucleate boiling) and the high temperature (film boiling) phases of boiling of a liquid over a heat generating element, also known as the boiling crisis. With the help of a simplified model, we demonstrate that the dangerous regime where the high temperature phase invades the whole system requires a larger heat power in a periodically spatially modulated system, than in a uniform system. The possibility that a local perturbation, such as a small gas bubble, may induce locally a transition to the film boiling state is also considered. We show that the transition to the film boiling regime is hindered in a spatially periodic system. (c) 2002 American Institute of Physics.

Journal Article↗
PubMed2001

[Improvement of a method for separation and determination of amino acids].

A method for separation and determination of amino acids using pre-column derivatization with 6-aminoquinoline-N-hydroxysuccinimido-carbamate (AccQ. Tag) was improved. The technique developed for rapid separation and determination of amino acids by AccQ. Tag method is described. The 18 amino acids and taurine are rapidly separated and determined by AccQ. Tag special chromatographic column(3.9 mm i.d. x 150 mm) within 17.5 min(the analysis period is 22.5 min) by changing the flow rate from 1.0 mL/min to 2.0 mL/min. In place of the AccQ. Tag special chromatographic column, the Nova-Pak C18 column(3.9 mm i.d. x 150 mm), Nova-Pak C18 column(4.6 mm i.d. x 150 mm), Symmetry C18 column(3.9 mm i.d. x 150 mm) or Waters Xterra RP-18 column, can be used to separate and determine the amino acids rapidly in the same manner. But among them the Symmetry C18 column is the best substitute for AccQ. Tag column. The separation time is 14.5 min and the analysis period is 20.0 min only. The price is much cheaper than the AccQ. Tag column.

Amino Acids↗
PubMedDate not supplied

Skill and selection bias has least influence on motor unit action potential firing rate/frequency.

INTRODUCTION: Motor unit action potential (MUAP) rise time in quantitative electromyography (QEMG) using multi-MUAP analysis may influence neuromuscular disease diagnosis. OBJECTIVE: To demonstrate in QEMG that MUAP firing rate/frequency (FR) is the parameter least dependent on electrodiagnostician skill (EDXc) skill and selection bias. METHODS AND MATERIALS: During minimal contraction (< 6 MUAPs/4.8 s analysis period) of tibialis anterior, 20 MUAPs were selected for QEMG at each of the 3 insertion sites. There were three EDXcs (professor & two fellows), each an independent MUAP selector + EMG machine itself (EMGM), for a total of four independent MUAP selectors. EDXc and selector order variation at each site involved the following. At insertion site1, during EMG by EDXc 1, the MUAP selector order was EDXc 1, EMGM, EDXc 2 and EDXc 3. At the following two sites, the previous 1st selector was sequentially rotated to become the last selector during EMG by the subsequent EDXc. The protocol was repeated in two subjects. MUAP inclusion criteria by EDXcs was MUAP rise time < 1 ms by visual inspection and, by the EMGM, any and all MUAPs during the 4.8 s analysis period. RESULTS: The reproducibility of measurements between MUAP selectors for mean frequency was satisfactory (correlation coefficient for inter-EDXc was 0.57, and 0.66 between the most experienced EDXc and EMGM. Inter- EDXc correlation coefficient was poor for amplitude (0.10), duration (0.34), size index (0.35), phases (-0.13) and turns (-0.22). Of the MUAPs collected by EMGM, the mean amplitude was smaller and mean duration was longer than those collected by the other 3 selectors with no significant differences for the other parameters. CONCLUSIONS: FR was the only satisfactorily reproduced parameter from QEMG of MUAPs between selectors, and least dependent on skill and/or selection bias. From this, FR appears a relatively objective parameter, while other parameters appear unduly influenced by EDXc skill and/or MUAP selection bias.

Action Potentials↗
PubMed2006

Updating long-term childhood cancer survival trend with period and mixed analysis: good news from population-based estimates in Italy.

An empirical evaluation of long-term period survival analysis was performed using data from the Childhood Cancer Registry of Piedmont, Italy. The aim was to update survival time trends and provide 25-year projections for children currently diagnosed with cancer. The observed survival experiences up to 15 years after diagnosis of five quinquennial cohorts (cohort analysis) were compared to the corresponding estimates obtained by period analysis. The two methods generally produced very similar findings, although period analysis estimates were slightly lower than those obtained from cohort analysis. We then used mixed analysis to assess time trends in long-term survival. This showed that the probability of surviving 25 years after a cancer in childhood has more than doubled compared to cohort analysis estimates from patients diagnosed more than 25 years ago (73% vs. 32%), providing further evidence of an ongoing improvement in prognosis.

Child↗
PubMed2005

High-density lipoprotein cholesterol as an indicator of liver function and prognosis in noncholestatic cirrhotics.

BACKGROUND AND AIMS: The liver plays a central role in production and degradation of lipoproteins. Declining lipoprotein cholesterol may reflect deteriorating liver function. METHODS: We reviewed the records of 248 veterans with noncholestatic cirrhosis followed in our clinics or referred for liver transplantation between January 1, 1997 and October 31, 2002 (analysis period) and confirmed our findings prospectively in 165 noncholestatic cirrhotic veterans newly referred for liver transplantation between November 1, 2002 and May 1, 2004 (validation period). RESULTS: In the analysis group, albumin, bilirubin, INR, and Model for End-Stage Liver Disease (MELD) score correlated strongly with high-density lipoprotein (HDL) cholesterol, weakly but significantly with total cholesterol and very-low-density lipoprotein cholesterol (VLDL), and poorly with low-density lipoprotein cholesterol (LDL). Transplant-free mortality at 90, 180, and 365 days was 17/201 (8.5%), 19/173 (11.0%), and 38/119 (31.9%), respectively. Death at all 3 time points was associated with significantly lower initial levels of HDL, VLDL, and total cholesterol, but not LDL cholesterol. Of the lipoproteins, HDL was the best predictor of survival at 180 and 365 days (concordance statistics .86+/-.05 and .78+/-.05, respectively). By multivariate logistic regression, HDL cholesterol and MELD score were independent predictors of survival at 6 and 12 months. By Cox regression, HDL cholesterol below 30 mg/dL was associated with 3.4-fold increase in the hazard ratio for cirrhotic death. In the validation period, HDL cholesterol was confirmed to be significantly associated with death or transplantation at 6 or 12 months. CONCLUSIONS: HDL cholesterol in noncholestatic cirrhotic patients is a liver function test and an indicator of prognosis.

Biomarkers↗
PubMed2004

A meta-analysis of periodized versus nonperiodized strength and power training programs.

The purpose of this study was to quantitatively combine and examine the results of studies examining the effectiveness of periodized (PER) compared to nonperiodized (Non-PER) training programs for strength and/or power development. Two analyses were conducted to (a) examine the magnitude of treatment effect elicited by PER strength training programs compared to Non-PER programs and (b) compare these effects after controlling for training volume, frequency, and intensity. Studies meeting the inclusion criteria were coded based on characteristics that might moderate the overall effects (i.e., participant characteristics and characteristics related to the training program). Effect sizes (ESs) were calculated for each study, and an overall ES of 0.84 (+/- 1.41) favoring PER training was found. Further analyses identified the treatment effect specific to training variation to be ES = 0.25. Significant moderating variables included age, training status, and length of training program. As a result of this statistical review of the literature, it is concluded that PER training is more effective than Non-PER training for men and women, individuals of varying training backgrounds, and for all age groups. In line with the overload principle, additions to volume, intensity, and frequency result in additional training adaptations.

Exercise↗
PubMed2001

Intensity of exposure and severity of whooping cough.

OBJECTIVE: To study the association between intensity of exposure and mortality due to pertussis. METHODS: Overall 3233 historical records from the main fever hospital in Copenhagen were examined. Exposure status of the whooping cough cases was coded as primary, secondary or multiple cases according to information in the hospital records. Primary cases, infected outside the home, were presumably exposed less intensively to the infectious agent compared to secondary cases, who were infected in the family. Multiple cases were from families with several simultaneous cases, but no clear information on transmission between cases. RESULTS: Case fatality was strongly related to age, being highest among the infants. Other risk factors were sibship size, exposure status and calendar period. In a multivariate analysis, period, age, and exposure status remained significant. Compared to primary cases, secondary cases and multiple cases had a 2.8 [RR = 2.76 (1.37 - 5.56)] and a two-fold [(RR = 1.99 (1.33 - 2.96)] higher risk of dying. CONCLUSION: Intensity of exposure may be a major determinant of the severity of pertussis infection.

Adolescent↗
PubMed1997

Cardiopulmonary effects of carfentanil in dama gazelles (Gazella dama).

Sixteen (10 female, six male) captive-born dama gazelles (Gazella dama) weighing 48 +/- 10 kg (mean +/- SD) were used to evaluate the cardiopulmonary effects of i.m. carfentanil and to validate the use of pulse oximetry in immobilized gazelles. Carfentanil (18.4 +/- 2.2 micrograms/kg i.m.) produced rapid induction (6 +/- 3 min), moderate muscle relaxation, and a significant (P < 0.05) decrease in heart rate (87 +/- 12 beats/min) beginning 5 min following induction and continuing throughout the immobilization period. A decrease in respiratory rates began 15 min following induction (11 +/- 4 breaths/min). Systemic hypertension was present throughout the immobilization period. Arterial blood gas analysis, performed at 10, 20, and 30 min after induction, showed PaCO2 and PaO2 values within normal limits. Arterial blood oxygen saturation (SaO2) was < 95% 10 min after induction. Relative arterial oxygen saturation (SpO2) values indicated by pulse oximetry were generally lower than SaO2 values but reliably demonstrated trends in arterial oxygen saturation as confirmed by arterial blood gas analysis. Periods of hypoxemia were usually indicated by the pulse oximeter reading and confirmed by SaO2 measurements. There was an increase in creatine phosphokinase values (88 +/- 53 U/L to 109 +/- 48 U/L) at 30 min postimmobilization. Naltrexone reversal (1.8 +/- 0.3 mg/kg, half i.v. and half s.c.) was rapid and uneventful, and time to standing was 2 +/- 1 min.

Analgesics, Opioid↗