Individual causal models and population system models in epidemiology

A group of individuals behaves as a population system when patterns of connections among individuals influence population health outcomes. Epidemiology usually treats populations as collections of independent individuals rather than as systems of interacting individuals. An appropriate theoretical structure, which includes the determinants of connections among individuals, is needed to develop a "population system epidemiology." Infection transmission models and sufficient-component cause models provide contrasting templates for the needed theoretical structure. Sufficient-component cause models focus on joint effects of multiple exposures in individuals. They handle time and interactions between individuals in the definition of variables and assume that populations are the sum of their individuals. Transmission models, in contrast, model interactions among individuals over time. Their nonlinear structure means that population risks are not simply the sum of individual risks. The theoretical base for "population system epidemiology" should integrate both approaches. It should model joint effects of multiple exposures in individuals as time related processes while incorporating the determinants and effects of interactions among individuals. Recent advances in G-estimation and discrete individual transmission model formulation provide opportunities for such integration.

The impact of radiotherapy dose and other treatment-related and clinical factors on in-field control in stage I and II non-Hodgkin's lymphoma

PURPOSE/OBJECTIVE

To assess local (in-field) disease control, identify potential prognostic factors, and elucidate the optimal radiotherapy dose in various clinical settings of Stage I and II non-Hodgkin's lymphoma (non-CNS).

MATERIALS & METHODS

A total of 285 consecutive patients with Stage I and II non-Hodgkin's lymphoma were treated with curative intent, including 159 with radiotherapy (RT) alone and 126 with combined-modality therapy (CMT). Of these, 72 patients had low-grade lymphomas (LGL), 92 had intermediate or high-grade lymphomas (I/HGL), and 21 had unclassified lymphomas. Clinical and treatment variables with potential prognostic significance for in-field disease control, freedom from relapse (FFR), and absolute survival (AS) were evaluated by univariate and multivariate analyses.

RESULTS

The 5-, 10-, and 20-year actuarial AS rates were 73%, 46%, and 33% for patients with LGL and 64%, 44%, and 18% for patients with I/HGL, respectively. The 5-, 10-, and 20-year actuarial FFR rates were 62%, 59%, and 49% for patients with LGL and 66%, 57%, and 57% for patients with I/HGL, respectively. Significant prognostic factors identified by the multivariate analysis were age, tumor size, and histology for AS; tumor size and treatment for FFR; and only tumor size for in-field disease control. There were 95 total failures, with only 12 occurring infield. Most failures (65%) were in contiguous unirradiated sites. All 4 in-field failures in patients with LGL occurred after RT doses < 30 Gy, although none occurred in 10 patients with small-volume LGL of the orbit treated with doses < 30 Gy. The 8 in-field failures in patients with I/HGL were distributed evenly throughout the RT dose range; 5 occurred in patients treated with CMT, all with tumors > 6 cm, and 4 with less than a complete response (CR) to chemotherapy.

CONCLUSION

Our analysis suggests that the overwhelming problem in the treatment of non-Hodgkin's lymphoma is not in-field failure but, rather, failure in contiguous unirradiated sites. A dose of 20-25 Gy may be sufficient for small-volume LGL of the orbit. A dose of 30 Gy is sufficient for LGL in general, as well as for patients with nonbulky (< or = 6 cm) I/HGL treated with CMT who have a CR. However, patients with I/HGL treated with CMT for tumors > 6 cm and/or without a CR may benefit from doses > or = 40 Gy.

Extended Rituximab (anti-CD20 monoclonal antibody) therapy for relapsed or refractory low-grade or follicular non-Hodgkin's lymphoma

BACKGROUND

Rituximab is a chimeric monoclonal antibody directed against the B-cell CD20 antigen which has been utilized for therapy of B-cell non-Hodgkin's lymphoma (NHL). A previous clinical trial demonstrated that treatment with four weekly doses of 375 mg/m2 of Rituximab in patients with relapsed or refractory low-grade or follicular B-cell non-Hodgkin's lymphoma was well tolerated and had significant clinical activity.

PATIENTS AND METHODS

To assess the safety and efficacy of Rituximab treatment, an open-label, single-arm, multi-center, phase II study of eight consecutive weekly infusions of 375 mg/m2 Rituximab in patients with low-grade or follicular B-cell NHL who had relapsed or had failed primary therapy was conducted. Thirty-seven patients with a median age of 55 years were treated.

RESULTS

Grade 1 or 2 adverse events were the majority of reported toxicities and occurred most frequently with the first infusion, decreasing with subsequent infusions. No patients developed a host antibody response (HACA) to Rituximab. The mean serum immunoglobulin levels for IgG, IgA, and IgM stayed within the normal range throughout the study. The majority of patients who were bcl-2 positive at baseline in peripheral blood became bcl-2 negative during treatment and remained negative at the time of B-cell recovery. In the 37 intent-to-treat patients, 5 (14%) had a complete response and 16 (43%) had a partial response for an overall response rate of 57%. Of 35 evaluable patients, 21 (60%) responded to treatment (14% CR and 46% PR). In responders, the median time to progression (TTP) and the median response duration have not been reached after 19.4+ months and 13.4+ months, respectively.

CONCLUSIONS

The safety profile and efficacy achieved in this pilot study of extended treatment with Rituximab compares favorably with those seen with four weekly doses. Further studies are warranted to investigate whether this or other extended Rituximab schedules will result in increased efficacy in all or in certain subgroups of patients with low-grade or follicular NHL.

Comparison of autologous peripheral blood stem cell dosing by ideal vs actual body weight

In this retrospective study, we evaluated the predictability of PBSC dose for hematopoietic engraftment comparing that calculated by ideal body weight (IBW) vs another calculated by actual body weight (ABW) for each patient. Sixty-three consecutive patients treated similarly using one transplant protocol were analyzed. While all patients had data available on CFU-GM and nucleated cells (NC), data on CD34+ enumeration was present only in 34 patients. We found that 49% of the patients were greater than 25% over their IBW. In addition, least-squares linear regression was used to assess the strength of the linear relationship between the inverse of cell dose/kg of ABW or IBW and time to AGC or platelet engraftment and showed no difference in r2 values for platelet engraftment, while using dose/kg of IBW greatly improved the ability of NC (r2 improved from 0.19 for ABW to 0.35 for IBW) and CFU-GM (r2 improved from 0.35 for ABW to 0.53 for IBW) to predict time to AGC engraftment, but did not change the CD34 r2. Hazard ratios were estimated using Cox proportional hazards regression and in all instances were found greater than 1.0 indicating that the probability of engraftment increased as cell dose/kg ABW or IBW increased. Finally, our data showed that 10 patients (16%) could have had one less apheresis procedure performed to obtain their set target stem cell dose calculated per kg IBW rather than ABW. In conclusion, PBSC dose per kg IBW is as good or better predictor of engraftment of AGC and may lead to cost savings in a certain subset of patients.

Non-Hodgkin's lymphoma of the head and neck: a 30-year experience at the University of Florida

BACKGROUND

Outcome in previously untreated patients with non-Hodgkin's lymphoma of the head and neck needed to be assessed.

METHODS

A retrospective review was performed of 79 patients with stage I or II non-Hodgkin's lymphoma of the head and neck treated between 1964 and 1994 with radiotherapy (RT) or combined modality therapy (CMT) at the University of Florida. Freedom from relapse, cause-specific survival, and absolute survival were analyzed by the Kaplan-Meier method. Patterns of failure were defined, and the relationship between dose and infield recurrence was studied. Histology was classified as low grade or intermediate/high grade.

RESULTS

At 10 years, absolute survival for patients with low-grade lymphoma treated with RT was 45%; absolute survival for patients with intermediate/high-grade lymphoma was 41% for those treated with RT and 57% for those who received CMT. Twenty-seven patients had a recurrence of lymphoma after initial treatment. Twenty patients (74%) had recurrences outside the radiation treatment field; 90% of these failures were in predictable sites that would be included in comprehensive lymphatic irradiation fields (Waldeyer's ring, mantle, and whole abdomen). No clear dose response was observed. Multivariate analysis showed that patients with tumors <5 cm in diameter had improved cause-specific survival, absolute survival, and freedom from relapse compared with patients with tumors > or = 5 cm in diameter.

CONCLUSIONS

Patients with non-Hodgkin's lymphoma in the head and neck with tumors > or = 5 cm in diameter appear to have a worse prognosis than those with smaller tumors. The patterns of failure suggest that initial treatment with comprehensive lymphatic irradiation fields could potentially eliminate the majority of treatment failures.

An analysis of odorant-induced currents in on-cell patches on mammalian olfactory receptor neurons

Because of the difficulty of obtaining odorant-induced currents in mammalian olfactory receptor neurons using whole-cell recording, we have developed a mathematical model of the electrical circuit of the patch and rest-of-cell. This can be used to quantitatively analyze on-cell patch pipette currents in response to perfusion of the cell by solutions containing odorants or other compounds that can alter membrane conductance or cell potential. We have analyzed pipette currents from on-cell patches of olfactory receptor neurons (ORNs) dissociated from adult rats. Initially, we perfused the ORNs with a high (100 mM; control 10 mM) KCl solution, which immediately induced a current flux from cell to pipette of a magnitude to imply a depolarization of approximately 52 mV, close to the value predicted from the Nernst equation (56 mV), and no change in the patch conductance. In contrast, perfusion by a cocktail of five cyclic adenosine-3',5'-monophosphate (cAMP)-stimulating odorants (cineole, n-amyl acetate, methyl salicylate, limonene and alpha-pinene, each at a concentration of 1 mM), after a delay of 4-10 sec, induced a current flux from pipette into the cell. Data in normal [Ca2+] and [Mg2+] implied an average patch conductance increase of approximately 36 pS, a cell depolarization of approximately 13 mV and an odorant-induced single channel conductance of approximately 16 pS. In low [Ca2+] and no Mg2+ approximately 40% of cells responded to odorants, with an induced current flow from cell to pipette implying a patch conductance increase of approximately 115 pS and cell depolarization of approximately 32 mV. The results were consistent with the odorants gating cAMP-gated cation channels. This analytical approach, which enables estimates of odorant-induced voltage and conductance changes to be made from changes in pipette current, should also be of general use for comparing cell responses to different perfusing solutions.

Zinc potentiation of the glycine receptor chloride channel is mediated by allosteric pathways

Molecular mechanisms of zinc potentiation were investigated in recombinant human alpha1 glycine receptors (GlyRs) by whole-cell patch-clamp recording and [3H]strychnine binding assays. In the wild-type (WT) GlyR, 1 microM zinc enhanced the apparent binding affinity of the agonists glycine and taurine and reduced their concentrations required for half-maximal activation. Thus, in the WT GlyR, zinc potentiation apparently occurs by enhancing agonist binding. However, analysis of GlyRs incorporating mutations in the membrane-spanning domain M1-M2 and M2-M3 loops, which are both components of the agonist gating mechanism, indicates that most mutations uncoupled zinc potentiation from glycine-gated currents but preserved zinc potentiation of taurine-gated currents. One such mutation in the M2-M3 loop, L274A, abolished the ability of zinc to potentiate taurine binding but did not inhibit zinc potentiation of taurine-gated currents. In this same mutant where taurine acts as a partial agonist, zinc potentiated taurine-gated currents but did not potentiate taurine antagonism of glycine-gated currents, suggesting that zinc interacts selectively with the agonist transduction pathway. The intracellular M246A mutation, which is unlikely to bind zinc, also disrupted zinc potentiation of glycine currents. Thus, zinc potentiation of the GlyR is mediated via allosteric mechanisms that are independent of its effects on agonist binding.

Nitric oxide inhibition of the rat olfactory cyclic nucleotide-gated cation channel

The effects of nitric oxide (NO) and other cysteine modifying agents were examined on cyclic nucleotide-gated (CNG) cation channels from rat olfactory receptor neurons. The NO compounds, S-nitroso-cysteine (SNC) and 3-morpholino-sydnonomine (SIN-1), did not activate the channels when applied for up to 10 min. The cysteine alkylating agent, N-ethylmaleimide (NEM), and the oxidising agent, dithionitrobensoate (DTNB), were also without agonist efficacy. Neither SNC nor DTNB altered the cAMP sensitivity of the channels. However, 2-min applications of SIN-1, SNC and DTNB inhibited the cAMP-gated current to approximately 50% of the control current level. This inhibition showed no spontaneous reversal for 5 min but was completely reversed by a 2-min exposure to DTT. The presence of cAMP protected the channels against NO-induced inhibition. These results indicate that inhibition is caused by S-nitrosylation of neighboring sulfhydryl groups leading to sulfhydryl bond formation. This reaction is favored in the closed channel state. Since recombinantly expressed rat olfactory alpha and beta CNG channel homomers and alpha/beta heteromers are activated and not inhibited by cysteine modification, the results of this study imply the existence of a novel subunit or tightly bound factor which dominates the effect of cysteine modification in the native channels. As CNG channels provide a pathway for calcum influx, the results may also have important implications for the physiological role of NO in mammalian olfactory receptor neurons.

Weight gain and the risk of developing insulin resistance syndrome

OBJECTIVE

Obesity and weight gain have been associated independently with hypertension, hyperinsulinemia, and dyslipidemia; however, prior research has not looked at the relation between weight gain from early adulthood to middle age and the development of this cluster of risk factors, known as insulin resistance syndrome.

RESEARCH DESIGN AND METHODS

The association between weight gain over 30 years (defined as the difference between measured weight in middle age and participant recall of their weight at age 20) and the odds of developing insulin resistance syndrome at middle age was examined in a population-based sample of 2,272 eastern Finnish men.

RESULTS

Each 5% increase in weight over the reported weight at age 20 was associated with nearly a 20% greater risk of insulin resistance syndrome by middle age, after adjustment for age and height. Moreover, there was a strong graded association between categories of weight gain and risk of insulin resistance syndrome. Men with weight increases of 10-19%, 20-29%, or > or =30% since age 20 were 3.0, 4.7, or 10.6 times more likely to have insulin resistance syndrome, respectively, by middle age, compared with men within 10% of their weight at age 20. Adjustments for age, height, physical activity, smoking, education, and parental history of diabetes did not alter these findings.

CONCLUSIONS

The odds of having developed the hemodynamic and metabolic abnormalities that characterize insulin resistance syndrome by middle adulthood were increasingly higher the greater the weight gain over the preceding 30 years. This study adds to the literature identifying deleterious effects of weight gain from young to middle adulthood.

Macro-to-micro links in the relation between income inequality and mortality

A growing literature points to links between income inequality and mortality. Any examination of the link should distinguish, both theoretically and empirically, between shifts in inequality that result from changes in the bottom and top of the income distribution. When state-level data from the U.S. censuses of 1980 and 1990 were used to measure differences in mortality, the results indicated that inequality measures reflecting depth of poverty show stronger correlations with mortality than do inequality measures reflecting heights of affluence. In addition, longitudinal data from the Panel Study of Income Dynamics were used to related state-level inequality measures to individual-level data on mortality. This comparison revealed significant associations between degree of income inequality in state of residence and individual risk of death only for nonelderly individuals with middle-class incomes in 1990.

Income inequality and mortality in metropolitan areas of the United States

OBJECTIVES

This study examined associations between income inequality and mortality in 282 US metropolitan areas.

METHODS

Income inequality measures were calculated from the 1990 US Census. Mortality was calculated from National Center for Health Statistics data and modeled with weighted linear regressions of the log age-adjusted rate.

RESULTS

Excess mortality between metropolitan areas with high and low income inequality ranged from 64.7 to 95.8 deaths per 100,000 depending on the inequality measure. In age-specific analyses, income inequality was most evident for infant mortality and for mortality between ages 15 and 64.

CONCLUSIONS

Higher income inequality is associated with increased mortality at all per capita income levels. Areas with high income inequality and low average income had excess mortality of 139.8 deaths per 100,000 compared with areas with low inequality and high income. The magnitude of this mortality difference is comparable to the combined loss of life from lung cancer, diabetes, motor vehicle crashes, human immunodeficiency virus (HIV) infection, suicide, and homicide in 1995. Given the mortality burden associated with income inequality, public and private sector initiatives to reduce economic inequalities should be a high priority.

Does low socioeconomic status potentiate the effects of heightened cardiovascular responses to stress on the progression of carotid atherosclerosis?

OBJECTIVES

This study examined whether heightened cardiovascular reactivity and low socioeconomic status had synergistic effects on the progression of carotid atherosclerosis in a population of eastern Finnish men.

METHODS

Data from the Kuopio Ischemic Heart Disease Risk Factor Study were used to measure 4-year progression of intima-media thickness in 882 men according to cardiovascular reactivity and socioeconomic status. Associations were examined in relation to risk factors and were stratified by baseline levels of atherosclerosis and prevalent ischemic heart disease.

RESULTS

The effect of reactivity on atherosclerotic progression depended on socioeconomic status. Men who had heightened cardiovascular responsiveness to stress and were born into poor families, received little education, or had low incomes had the greatest atherosclerotic progression.

CONCLUSIONS

An understanding of associations between individual risk factors and disease should be based on etiologic hypotheses that are conceived at the population level and involve fundamental social and economic causes of disease. This study demonstrates how examining the interaction of an individual biological predisposition will low socioeconomic status over the life course is etiologically informative for understanding the progression of atherosclerotic vascular disease.

Characterization of calcium-activated chloride channels in patches excised from the dendritic knob of mammalian olfactory receptor neurons

We investigated the properties of calcium-activated chloride channels in inside-out membrane patches from the dendritic knobs of acutely dissociated rat olfactory receptor neurons. Patches typically contained large calcium-activated currents, with total conductances in the range 30-75 nS. The dose response curve for calcium exhibited an EC50 of about 26 microM. In symmetrical NaCl solutions, the current-voltage relationship reversed at 0 mV and was linear between -80 and +70 mV. When the intracellular NaCl concentration was progressively reduced from 150 to 25 mM, the reversal potential changed in a manner consistent with a chloride-selective conductance. Indeed, modeling these data with the Goldman-Hodgkin-Katz equation revealed a PNa/PCl of 0.034. The halide permeability sequence was PCl > PF > PI > PBr indicating that permeation through the channel was dominated by ion binding sites with a high field strength. The channels were also permeable to the large organic anions, SCN-, acetate-, and gluconate-, with the permeability sequence PCl > PSON > Pacetate > Pgluconate. Significant permeation to gluconate ions suggested that the channel pore had a minimum diameter of at least 5.8 A.

Cumulative impact of sustained economic hardship on physical, cognitive, psychological, and social functioning

BACKGROUND

Although the relation between low income and poor health is well established, most previous research has measured income at only one time.

METHODS

We used income information collected in 1965, 1974, and 1983 from a representative sample of adults in Alameda County, California, to examine the cumulative effect of economic hardship (defined as a total household income of less than 200 percent of the federal poverty level) on participants who were alive in 1994.

RESULTS

Because of missing information, analyses were based on between 1081 and 1124 participants (median age, 65 years in 1994). After adjustment for age and sex, there were significant graded associations between the number of times income was less than 200 percent of the poverty level (range, 0 to 3) and all measures of functioning examined except social isolation. As compared with subjects without economic hardship, those with economic hardship in 1965, 1974, and 1983 were much more likely to have difficulties with independent activities of daily living (such as cooking, shopping, and managing money) (odds ratio, 3.38; 95 percent confidence interval, 1.49 to 7.64), activities of daily living (such as walking, eating, dressing, and using the toilet) (odds ratio, 3.79; 95 percent confidence interval, 1.32 to 9.81), and clinical depression (odds ratio, 3.24; 95 percent confidence interval, 1.32 to 7.89) in 1994. We found little evidence of reverse causation -- that is, that episodes of illness might have caused subsequent economic hardship.

CONCLUSIONS

Sustained economic hardship leads to poorer physical, psychological, and cognitive functioning.

A clinical tool for rating response to civil commitment for substance abuse treatment

OBJECTIVE

The objectives of this study were to develop a measure to assess patients' response to civil commitment, to test this measure on two groups of dually diagnosed patients (medically ill alcoholics and patients with dual mental and substance use disorders), and to identify patient characteristics associated with a positive response to commitment.

METHODS

The outcome of 38 male veterans civilly committed to inpatient substance abuse treatment for an average of six months was rated by their treating clinicians. Raters used the Commitment Response Form (CRF), a scale anchored to behavioral descriptions that was developed for the study and that measures outcome in five areas: patients' attitude toward recovery, substance use, medical condition, engagement in substance abuse treatment, and independence of functioning. Each patient's medical records were reviewed by two clinical staff members who made independent retrospective ratings and a joint rating using the CRF. They also made independent and joint dichotomous ratings of whether the patient was a positive responder or a nonresponder to civil commitment.

RESULTS

The CRF showed superior reliability when compared with the dichotomous rating of outcome. The scale demonstrated reasonable psychometric properties. Mean scale scores did not differ significantly by patient group; slightly more than half were rated as having a good to excellent overall response. Better outcome was associated with longer periods of previous abstinence from alcohol and a higher level of education.

CONCLUSIONS

Use of a scale anchored to behavioral descriptions improved reliability of outcome determinations by clinical staff. Civil commitment resulted in good to excellent outcome in many but not all committed patients.

Concentration dependence of sodium permeation and sodium ion interactions in the cyclic AMP-gated channels of mammalian olfactory receptor neurons

The dependence of currents through the cyclic nucleotide-gated (CNG) channels of mammalian olfactory receptor neurons (ORNs) on the concentration of NaCl was studied in excised inside-out patches from their dendritic knobs using the patch-clamp technique. With a saturating concentration (100 microM) of adenosine 3',5'-cyclic monophosphate (cAMP), the changes in the reversal potential of macroscopic currents were studied at NaCl concentrations from 25 to 300 mM. In symmetrical NaCl solutions without the addition of divalent cations, the current-voltage relations were almost linear, reversing close to 0 mV. When the external NaCl concentration was maintained at 150 mM and the internal concentrations were varied, the reversal potentials of the cAMP-activated currents closely followed the Na+ equilibrium potential indicating that PCl/PNa approximately 0. However, at low external NaCl concentrations (< or = 100 mM) there was some significant chloride permeability. Our results further indicated that Na+ currents through these channels: (i) did not obey the independence principle; (ii) showed saturation kinetics with K(m)s in the range of 100-150 mM and (iii) displayed a lack of voltage dependence of conductance in asymmetric solutions that suggested that ion-binding sites were situated midway along the channel. Together, these characteristics indicate that the permeation properties of the olfactory CNG channels are significantly different from those of photoreceptor CNG channels.

Is combined modality therapy necessary for advanced Hodgkin's disease?

PURPOSE

To determine whether single-modality therapy is optimal management for patients with Stage III-IV Hodgkin's disease.

METHODS AND MATERIALS

All patients with advanced (Stage III and IV) Hodgkin's disease treated at the University of Florida from 1964 through 1989 (n = 141) were studied retrospectively for factors predictive of good outcome with single-modality therapy. Treatment modalities varied and were distributed as follows: combined-modality therapy (CMT), 55 patients; chemotherapy alone (CX), 50 patients; and radiotherapy alone (RT), 36 patients.

RESULTS

Ten-year rates of freedom from relapse and overall survival for all Stage III patients were 66% and 59% compared with 36% and 35% for Stage IV patients. The RT subset was highly selected with the majority of patients having nonbulky Stage IIIA disease. Within the RT group, multivariate analysis identified the degree of splenic involvement and age as the factors most associated with freedom from relapse. In patients treated with CX, multivariate analysis identified bulky tumor (maximum transverse tumor dimension > 6 cm) as the most important prognostic factor for relapse. In patients without bulky disease (< or = 6 cm), the probabilities of freedom from relapse and overall survival at 10 years, respectively, according to treatment group were 53% and 58% for RT patients, 60% and 56% for CX patients, and 83% and 71% for CMT patients. For patients without bulky disease, the probability of freedom from relapse was significantly better for the CMT group than for CX patients (p = 0.03) or RT patients (p = 0.04), but there was no statistical difference in overall survival among the three groups. In patients with bulky disease (> 6 cm), the probabilities of freedom from relapse and overall survival at 10 years were 44% and 45% for RT patients, 9% and 0% for CX patients, and 72% and 58% for CMT patients. Freedom from relapse and overall survival were significantly better (p = 0.0001) for CMT patients compared with CX patients. Fatal hematopoietic disorders developed in 10 patients: 2 of 36 RT patients, 2 of 50 CX patients, and 6 of 55 CMT patients. Nine patients had received chemotherapy, and eight had six or more cycles of alkylator-based chemotherapy.

CONCLUSION

This retrospective study suggests that combined-modality therapy is preferable to single-modality therapy in the majority of patients with advanced Hodgkin's disease.

Is comprehensive lymphatic irradiation for low-grade non-Hodgkin's lymphoma curative therapy? Long-term experience at a single institution

PURPOSE

This study reports 21 patients with Stage I-III low-grade non-Hodgkin's lymphoma who were treated with comprehensive lymphatic irradiation (CLI) at the University of Florida between 1966 and 1992.

METHODS AND MATERIALS

Sites clinically involved with disease were treated with 30 Gy, whereas clinically uninvolved sites were treated with 25 Gy. Median follow-up for the group was 14 years (24.5 years for Stage III patients).

RESULTS

Overall absolute survival rates at 5, 10, and 15 years were 84%, 68%, and 34%. Cause-specific survival rates at 5, 10, and 15 years were 84%, 68%, and 56%. Freedom-from-relapse rates at 5, 10, and 15 years were 75%, 58%, and 58%, with no relapses noted after 10 years. Bulky disease (>6 cm) was a significant indicator of poor prognosis for cause-specific survival (p = .01).

CONCLUSION

These data support findings from other institutions suggesting a role for CLI as potentially curative therapy with acceptable toxicity and a short treatment time for patients with Stages I and II and limited Stage III disease.

Why do poor people behave poorly? Variation in adult health behaviours and psychosocial characteristics by stages of the socioeconomic lifecourse

Attempts to explain socioeconomic inequalities in health have often made reference to the observation that poor health behaviours and psychosocial characteristics cluster in low socioeconomic status (SES) groups. Causal interpretation of the association between SES, health behaviour, psychosocial orientations, and health inequalities has been hampered because these factors and SES have usually been measured at the same point in time. Data from the Kuopio Ischaemic Heart Disease Risk Factor Study were used to examine the associations between measures of SES reflecting different stages of the lifecourse, health behaviours, and psychosocial characteristics in adulthood in a population-based study of 2674 middle-aged Finnish men. Results show that many adult behaviours and psychosocial dispositions detrimental to health are consistently related to poor childhood conditions, low levels of education, and blue-collar employment. Poor adult health behaviours and psychosocial characteristics were more prevalent among men whose parents were poor. Increases in income inequality which place children into low SES conditions may well produce a negative behavioural and psychosocial health dividend to be reaped in the future. Understanding that adult health behaviour and psychosocial orientations are associated with socioeconomic conditions throughout the lifecourse implies that efforts to reduce socioeconomic inequalities in health must recognize that economic policy is public health policy.

Odorant-induced currents in intact patches from rat olfactory receptor neurons: theory and experiment

Odorant-induced currents in mammalian olfactory receptor neurons have proved difficult to obtain reliably using conventional whole-cell recording. By using a mathematical model of the electrical circuit of the patch and rest-of-cell, we demonstrate how cell-attached patch measurements can be used to quantitatively analyze responses to odorants or a high (100 mM) K+ solution. High K+ induced an immediate current flux from cell to pipette, which was modeled as a depolarization of approximately 52 mV, close to that expected from the Nernst equation (56 mV), and no change in the patch conductance. By contrast, a cocktail of cAMP-stimulating odorants induced a current flux from pipette into cell following a significant (4-10 s) delay. This was modeled as an average patch conductance increase of 36 pS and a depolarization of 13 mV. Odorant-induced single channels had a conductance of 16 pS. In cells bathed with no Mg2+ and 0.25 mM Ca2+, odorants induced a current flow from cell to pipette, which was modeled as a patch conductance increase of approximately 115 pS and depolarization of approximately 32 mV. All these results are consistent with cAMP-gated cation channels dominating the odorant response. This approach, which provides useful estimates of odorant-induced voltage and conductance changes, is applicable to similar measurements in any small cells.

Interaction of workplace demands and cardiovascular reactivity in progression of carotid atherosclerosis: population based study

OBJECTIVE

To examine the combined influence of workplace demands and changes in blood pressure induced by stress on the progression of carotid atherosclerosis.

DESIGN

Population based follow up study of unestablished as well as traditional risk factors for carotid atherosclerosis, ischaemic heart disease, and other outcomes.

SETTING

Eastern Finland.

SUBJECTS

591 men aged 42-60 who were fully employed at baseline and had complete data on the measures of carotid atherosclerosis, job demands, blood pressure reactivity, and covariates.

MAIN OUTCOME MEASURES

Change in ultrasonographically assessed intima-media thickness of the right and left common carotid arteries from baseline to 4 year follow up.

RESULTS

Significant interactions between workplace demands and stress induced reactivity were observed for all measures of progression (P < 0.04). Men with large changes in systolic blood pressure (20 mm Hg or greater) in anticipation of a maximal exercise test and with high job demands had 10-40% greater progression of mean (0.138 v 0.123 mm) and maximum (0.320 v 0.261 mm) intima-media thickness and plaque height (0.347 v 0.264) than men who were less reactive and had fewer job demands. Similar results were obtained after excluding men with prevalent ischaemic heart disease at baseline. Findings were strongest among men with at least 20% stenosis or non-stenotic plaque at baseline. In this subgroup reactive men with high job demands had more than 46% greater atherosclerotic progression than the others. Adjustment for atherosclerotic risk factors did not alter the results.

CONCLUSIONS

Men who showed stress induced blood pressure reactivity and who reported high job demands experienced the greatest atherosclerotic progression, showing the association between dispositional risk characteristics and contextual determinants of disease and suggesting that behaviourally evoked cardiovascular reactivity may have a role in atherogenesis.

Identification of intracellular and extracellular domains mediating signal transduction in the inhibitory glycine receptor chloride channel

Fast synaptic neurotransmission is mediated by transmitter-activated conformational changes in ligand-gated ion channel receptors, culminating in opening of the integral ion channel pore. Human hereditary hyperekplexia, or startle disease, is caused by mutations in both the intracellular or extracellular loops flanking the pore-lining M2 domain of the glycine receptor alpha1 subunit. These flanking domains are designated the M1-M2 loop and the M2-M3 loop respectively. We show that four startle disease mutations and six additional alanine substitution mutations distributed throughout both loops result in uncoupling of the ligand binding sites from the channel activation gate. We therefore conclude that the M1-M2 and M2-M3 loops act in parallel to activate the channel. Their locations strongly suggest that they act as hinges governing allosteric control of the M2 domain. As the members of the ligand-gated ion channel superfamily share a common structure, this signal transduction model may apply to all members of this superfamily.

The glycine receptor

The inhibitory glycine receptor (GlyR) is a member of the ligand-gated ion channel receptor superfamily. The GlyR comprises a pentameric complex that forms a chloride-selective transmembrane channel, which is predominantly expressed in the spinal cord and brain stem. We review the pharmacological and physiological properties of the GlyR and relate this information to more recent insights that have been obtained through the cloning and recombinant expression of the GlyR subunits. We also discuss insights into our understanding of GlyR structure and function that have been obtained by the genetic characterisation of various heritable disorders of glycinergic neurotransmission.

Do cardiovascular risk factors explain the relation between socioeconomic status, risk of all-cause mortality, cardiovascular mortality, and acute myocardial infarction?

Much remains to be understood about how low socioeconomic status (SES) increases cardiovascular disease and mortality risk. Data from the Kuopio Ischemic Heart Disease Risk Factor Study (1984-1993) were used to estimate the associations between acute myocardial infarction and income, all-cause mortality, and cardiovascular mortality in a population-based sample of 2,272 Finnish men, with adjustment for 23 biologic, behavioral, psychologic, and social risk factors. Compared with the highest income quintile, those in the bottom quintile had age-adjusted relative hazards of 3.14 (95% confidence interval (CI) 1.77-5.56), 2.66 (95% CI 1.25-5.66), and 4.34 (95% CI 1.95-9.66) for all-cause mortality, cardiovascular mortality, and AMI, respectively. After adjustment for risk factors, the relative hazards for the same comparisons were 1.32 (95% CI 0.70-2.49), 0.70 (95% CI 0.29-1.69), and 2.83 (95% CI 1.14-7.00). In the lowest income quintile, adjustment for risk factors reduced the excess relative risk of all-cause mortality by 85%, that of cardiovascular mortality by 118%, and that of acute myocardial infarction by 45%. These data show how the association between SES and cardiovascular mortality and all-cause mortality is mediated by known risk factor pathways, but full "explanations" for these associations will need to encompass why these biologic, behavioral, psychologic, and social risk factors are differentially distributed by SES.

Calcium-dependent modulation of the agonist affinity of the mammalian olfactory cyclic nucleotide-gated channel by calmodulin and a novel endogenous factor

The calcium-dependent modulation of the affinity of the cyclic nucleotide-gated (CNG) channels for adenosine 3',5'-cyclic monophosphate (cAMP) was studied in enzymatically dissociated rat olfactory receptor neurons, by recording macroscopic cAMP-activated currents from inside-out patches excised from their dendritic knobs. Upon intracellular addition of 0.2 mM Ca2+ (0.2 Ca) the concentration of cAMP required for the activation of half-maximal current (EC50) was reversibly increased from 3 microM to about 30 microM. This Ca2+-induced affinity shift was insensitive to the calmodulin antagonist, mastoparan, was abolished irreversibly by a 2-min exposure to 3 mm Mg2+ + 2 mm EGTA (Mg + EGTA), and was not restored by the application of calmodulin (CAM). Addition of CAM plus 0.2 mM Ca2+ (0.2 Ca + CAM), further reversibly shifted the cAMP affinity from 30 microM to about 200 microM. This affinity shift was not affected by Mg + EGTA exposure, but was reversed by mastoparan. Thus, the former Ca2+-only effect must be mediated by an unknown endogenous factor, distinct from CAM. Removal of this factor also increased the affinity of the channel for CAM. The affinity shift induced by Ca2+-only was maintained in the presence of the nonhydrolyzable cAMP analogue, 8-bromo-cAMP and the phosphatase inhibitor, microcystin-LR, ruling out modulation by phosphodiesterases or phosphatases. Our results indicate that the olfactory CNG channels are modulated by an as yet unidentified factor distinct from CAM.

A phase II trial of paclitaxel in the treatment of recurrent or metastatic soft tissue sarcomas or bone sarcomas

The study aimed to determine the activity and toxicity of taxol in the treatment of recurrent or metastatic soft tissue sarcomas or osteosarcomas. The major findings are that five patients had stable disease after two cycles of chemotherapy but two of these patients were subsequently removed from the study at their own request. The other three patients progressed after an additional two cycles of chemotherapy. Seven patients progressed during the first two cycles and were removed from the study. One patient completed only one cycle of therapy and was deemed inevaluable for study response. There were eight episodes of grade 3 or 4 neutropenia and two episodes of grade 3 thrombocytopenia. One patient experienced grade 3 neurological toxicity and one patient grade 3 mucositis. Two patients are currently alive with progressing disease and one patient is alive with no evidence of disease after undergoing surgery and radiotherapy. The principal conclusions are that Paclitaxel is ineffective in treating recurrent or metastatic soft tissue sarcoma and osteosarcoma. Treatment at this dose is quite myelosuppressive, but toxicity is generally manageable. Further study of this agent is not justified in this setting.

Inequality in income and mortality in the United States: analysis of mortality and potential pathways

OBJECTIVE

To examine the relation between health outcomes and the equality with which income is distributed in the United States.

DESIGN

The degree of income inequality, defined as the percentage of total household income received by the less well off 50% of households, and changes in income inequality were calculated for the 50 states in 1980 and 1990. These measures were then examined in relation to all cause mortality adjusted for age for each state, age specific deaths, changes in mortalities, and other health outcomes and potential pathways for 1980, 1990, and 1989-91.

MAIN OUTCOME MEASURE

Age adjusted mortality from all causes.

RESULTS

There was a significant correlation (r = -0.62 [corrected], P < 0.001) between the percentage of total household income received by the less well off 50% in each state and all cause mortality, unaffected by adjustment for state median incomes. Income inequality was also significantly associated with age specific mortalities and rates of low birth weight, homicide, violent crime, work disability, expenditures on medical care and police protection, smoking, and sedentary activity. Rates of unemployment, imprisonment, recipients of income assistance and food stamps, lack of medical insurance, and educational outcomes were also worse as income inequality increased. Income inequality was also associated with mortality trends, and there was a suggestion of an impact of inequality trends on mortality trends.

CONCLUSION

Variations between states in the inequality of the distribution of income are significantly associated with variations between states in a large number of health outcomes and social indicators and with mortality trends. These differences parallel relative investments in human and social capital. Economic policies that influence income and wealth inequality may have an important impact on the health of countries.

Stevens-Johnson syndrome resulting from whole-brain radiation and phenytoin

Phenytoin, one of the most widely prescribed anticonvulsants, and steroids are routinely utilized for seizure prophylaxis in patients with various intracranial tumors. We report a case of severe Stevens-Johnson syndrome (SJS), documented by biopsy, which occurred in a patient, with metastatic squamous cell carcinoma receiving phenytoin, whole-brain radiation therapy (WBRT), and a tapering steroid dose. The pathogenesis and implications are then briefly discussed.

The human glycine receptor beta subunit: primary structure, functional characterisation and chromosomal localisation of the human and murine genes

The inhibitory glycine receptor (GlyR) is a pentameric receptor comprised of alpha and beta subunits, of which the beta subunit has not been characterised in humans. A 2106 bp cDNA, isolated from a human hippocampal cDNA library, contained an open reading frame of 497 amino acids which encodes the beta subunit of the human GlyR. The mature human GlyR beta polypeptide displays 99% amino acid identity with the rat GlyR beta subunit and 48% identity with the human GlyR alpha 1 subunit. Neither [3H]strychnine binding nor glycine-gated currents were detected when the human GlyR beta subunit cDNA was expressed in the human embryonic kidney 293 cell line. However, co-expression of the beta subunit cDNA with the alpha 1 subunit cDNA resulted in expression of functional GlyRs which showed a 4-fold reduction in the EC50 values when compared to alpha 1 homomeric GlyRs. Glycine-gated currents of alpha 1/beta GlyRs were 17-fold less sensitive than homomeric alpha 1 GlyRs to the antagonists picrotoxin, picrotoxinin and picrotin, providing clear evidence that heteromeric alpha 1/beta GlyRs were expressed. The beta subunit appears to play a structural rather than ligand binding role in GlyR function. Fluorescence in situ hybridisation was used to localise the gene encoding the human GlyR beta subunit (GLRB) to chromosome 4q32, a position syntenic with mouse chromosome 3. In situ hybridisation using the human GlyR beta subunit cDNA showed that the murine GlyR beta subunit gene (Glrb) maps to the spastic (spa) locus on mouse chromosome 3 at bands E3-F1. This is consistent with the recent finding that a mutation in the murine GlyR beta subunit causes the spa phenotype. It also raises the possibility that mutations in the human beta subunit gene may cause inherited disorders of the startle response.

The permeation of organic cations through cAMP-gated channels in mammalian olfactory receptor neurons

The permeation of monovalent organic cations through adenosine 3',5'-cyclic monophosphate-(cAMP) activated channels was studied by recording macroscopic currents in excised inside-out membrane patches from the dendritic knobs of isolated mammalian olfactory receptor neurons (ORNs). Current-voltage relations were measured when bathing solution Na+ was replaced by monovalent organic cations. Permeability ratios relative to Na+ ions were calculated from changes in reversal potentials. Some of the small organic cations tested included ammonium (NH4+), hydroxylammonium and formamidinium, with relative permeability ratios of 1.41, 2.3 and 1.01 respectively. The larger methylated and ethylated ammonium ions studied included: DMA (dimethylammonium), TMA (tetramethylammonium) and TEA (tetraethylammonium) and they all had permeability ratios larger than 0.09. Even large cations such as choline, arginine and tris(hydroxymethyl)aminomethane (Tris) were appreciably permeant through the cAMP-activated channel with permeability ratios ranging from 0.19 to 0.7. The size of the permeating cations, as assessed by molecular weight, was a good predictor of the permeability. The permeability sequence of the cAMP-activated channel in our study was PNH4 > PNa > PDMA > PTMA > PCholine > PTEA. Higher permeability ratios of hydroxylammonium, arginine and tris(hydroxymethyl)aminomethane cannot be explained by ionic size alone. Our results indicate that: (i) cAMP-activated channels poorly select between monovalent cations; (ii) the pore dimension must be at least 6.5 x 6.5 A, in order to allow TEA and Tris to permeate and (iii) molecular sieving must be an important mechanism for the permeation of large organic ions through the channels with specific ion binding playing a smaller role than in other structurally similar channels. In addition, the results clearly indicate that cyclic nucleotide-gated (CNG) channels in different cells are not the same, the olfactory CNG channel being different from that of the photoreceptors, particularly with respect to the permeation of large organic cations, which the ORN channels allow to permeate readily.

Mutations affecting the glycine receptor agonist transduction mechanism convert the competitive antagonist, picrotoxin, into an allosteric potentiator

Contrary to its effects on the gamma-aminobutyric acid type A receptor, picrotoxin antagonism of the alpha 1 subunit of the human glycine receptor is shown to be competitive, not use-dependent, and nonselective between the picrotoxin components, picrotin, and picrotoxinin. Competitive antagonism and non-use dependence are consistent with picrotoxin binding to a site in the extracellular domain. The mutations Arg-->Leu or Arg-->Gln at residue 271 of the glycine receptor alpha 1 subunit, which are both associated with human startle disease, have previously been demonstrated to disrupt the transduction process between agonist binding and channel activation. We show here that these mutations also transform picrotoxin from an allosterically acting competitive antagonist to an allosteric potentiator at low (0.01-3 microM) concentrations and to a noncompetitive antagonist at higher (> or = 3 microM) concentrations. This demonstrates that arginine 271 is involved in the transduction process between picrotoxin binding and its mechanism of action. Thus, the allosteric transduction pathways of both agonists and antagonists converge at a common residue prior to the activation gate of the channel, suggesting that this residue may act as an integration point for information from various extracellular ligand binding sites.

Dietary intake of the short-chain triglyceride triacetin vs. long-chain triglycerides decreases adipocyte diameter and fat deposition in rats

Diets containing either triacetin (the water-soluble triglyceride of acetate) or long-chain triglycerides (LCT) were fed to rats for 30 d to determine the effect on body weight gain and adipose tissue cellularity. Male Sprague-Dawley rats were allowed free access to one of three diets: a control diet containing 5% of energy as fat or one of two experimental diets that contained 30% triglyceride (by energy). The source of the triglyceride in the two experimental groups was either 100% LCT or 95% triacetin + 5% LCT. Within the experimental groups receiving 30% fat, the source of dietary triglyceride (LCT vs. triacetin) did not affect total energy consumption. There were no significant differences in body weight at the onset of the study; however, animals fed 100% LCT weighed significantly more than the other two groups at the end of the study. In all three fat pads studied, animals fed triacetin had significantly lower pad mass than did animals fed LCT. Mean fat cell size was smaller in fat depots of animals fed short-chain triglyceride. Provision of dietary energy as the short-chain triglyceride triacetin in lieu of LCT resulted in lower weight gain and fat deposition. These data demonstrate the impact of dietary triglyceride composition on body weight regulation.

Mutation of an arginine residue in the human glycine receptor transforms beta-alanine and taurine from agonists into competitive antagonists

Agonist binding to the inhibitory glycine receptor (GlyR) initiates the opening of a chloride-selective channel that modulates the neuronal membrane potential. Point mutations of the GlyR, substituting Arg-271 with either Leu or Gln, have been shown to underlie the inherited neurological disorder startle disease (hyperekplexia). We show that these substitutions result in the redistribution of GlyR single-channel conductances to lower conductance levels. Additionally, the binding of the glycinergic agonists beta-alanine and taurine to mutated GlyRs does not initiate a chloride current, but instead competitively antagonizes currents activated by glycine. These findings are consistent with mutations of Arg-271 resulting in the uncoupling of the agonist binding process from the channel activation mechanism of the receptor.

Response to radiation in chemotherapy-refractory monocytoid B-cell lymphoma: a case report

A 39-year-old man had monocytoid lymphoma including a large retroperitoneal mass, retrocrural and porta hepatic adenopathy with localized pain, but no B symptoms. The tumor did not respond clinically or radiographically to CHOP or mini-ICE chemotherapy but has responded dramatically to radiotherapy. The patient's disease remains controlled 3 years after treatment. This case documents radioresponsiveness in a chemotherapy-refractory monocytoid lymphoma.

Startle disease mutations reduce the agonist sensitivity of the human inhibitory glycine receptor

The receptor for the inhibitory neurotransmitter glycine is a member of the ligand-gated ion channel receptor superfamily. Point mutations in the gene encoding the alpha 1 subunit of the glycine receptor-channel complex (GlyR) have recently been identified in pedigrees with the autosomal dominant neurological disorder, startle disease (hyperekplexia). These mutations result in the substitution of leucine or glutamine for arginine 271. This charged residue is located near the ion channel region and is predicted to affect chloride permeation through the GlyR. We found little evidence for this role from the anion/cation selectivity and lack of pronounced rectification of currents flowing through recombinant human alpha 1 subunit GlyRs containing the startle disease mutations. We reveal, however, that the startle disease mutations profoundly disrupt GlyR function by causing 230-410-fold decreases in the sensitivity of receptor currents activated by the agonist glycine. Additionally, we report corresponding 56- and 120-fold reductions in the apparent binding affinity (Ki) of glycine to the mutant GlyRs, but no change in the binding affinity of the competitive antagonist, strychnine. Thus, startle disease reduces the efficacy of glycinergic inhibitory neurotransmission by producing GlyRs with diminished agonist responsiveness. Our results show that startle disease mutations define a novel receptor activation site.

Pure red cell aplasia associated with angioimmunoblastic lymphadenopathy with dysproteinemia

Angioimmunoblastic lymphadenopathy with dysproteinemia (AILD) can best be described as a disorder of T-cells resulting in amplification of the B-cell response and clinical symptoms of lymphadenopathy, fever, hepatosplenomegaly, and a variety of blood abnormalities. Pure red cell aplasia (PRCA), an autoimmune disorder resulting in selective aplasia of the erythroid series, has only rarely been associated with AILD. Herein we report three cases of AILD and PRCA. Serum from one patient was available for study and contained a dose-dependent inhibitor of the CFU-E but not CFU-GM cultures from normal bone marrow. This activity was found in the globulin fraction after ammonium sulfate precipitation. Patients with AILD are known to make antibodies to many autologous epitopes, and the most well-characterized mechanism of PRCA involves antibodies to red cell precursors. Our serum data are consistent with the hypothesis that such an antibody existed in our patient. Aggressive treatment of these patients resulted in transient improvement in two; however, all three died without achieving a durable complete remission with two dying of infectious complications.

A missense mutation in the gene encoding the alpha 1 subunit of the inhibitory glycine receptor in the spasmodic mouse

Hereditary hyperekplexia, an autosomal dominant neurologic disorder characterized by an exaggerated startle reflex and neonatal hypertonia, can be caused by mutations in the gene encoding the alpha 1 subunit of the inhibitory glycine receptor (GLRA1). Spasmodic (spd), a recessive neurologic mouse mutant, resembles hyperekplexia phenotypically, and the two disease loci map to homologous chromosomal regions. Here we describe a Glra1 missense mutation in spd that results in reduced agonist sensitivity in glycine receptors expressed in vitro. We conclude that spd is a murine homologue of hyperekplexia and that mutations in GLRA1/Glra1 can produce syndromes with different inheritance patterns.

The role of prognostic factors in treatment selection for early-stage Hodgkin's disease

PURPOSE

To identify poor prognostic factors in early-stage Hodgkin's disease that predict a high rate of relapse after radiotherapy alone.

MATERIALS AND METHODS

A total of 153 patients with stages I and II supradiaphragmatic Hodgkin's disease, treated between 1964 and 1986 with either radiotherapy alone (120 patients) or combined modality therapy (33 patients), were studied retrospectively to determine factors affecting freedom from relapse and absolute survival. Median follow-up was 13 years. Clinical factors were assessed by the stepwise use of a stratified log-rank test and included maximum tumor dimension in any site (< or = 6 cm or > 6 cm), age (< or = 40 or > 40), presence or absence of B symptoms, pathologic and clinical stages (I or II), number of sites involved (< or = 4 or > 4), gender, histologic subtype, and large mediastinal mass (none, small [< or = 6 cm], large [> 6 cm]).

RESULTS

The only factors independently predicting a high rate of relapse were tumor dimension (> 6 cm) and number of sites (> 4 sites). At 10 years, in patients with and without the two poor prognostic factors treated with radiotherapy alone, the freedom from relapse rates were 53% and 84% (p < .0001) and the absolute survival rates were 72% and 85% (p = .004), respectively. Combined modality therapy significantly improved freedom from relapse, but not absolute survival, in patients with one or both poor prognostic factors.

CONCLUSIONS

Two poor prognostic factors were identified that were highly significant in predicting a high risk of relapse after radiotherapy alone. The addition of three cycles of chemotherapy to standard radiotherapy significantly reduced the relapse rate in high-risk patients.

Effects of the short-chain triglyceride triacetin on intestinal mucosa and metabolic substrates in rats

Diets containing either triacetin (the water-soluble triglyceride of acetate) or long-chain triglycerides (LCTs) were fed to rats to determine the effects on intestinal mucosa cells and plasma substrates. Male Sprague-Dawley rats were fed one of three diets, a control diet containing 5% of energy as LCTs or one of two experimental diets that contained 30% of energy as lipid. The lipid component of the two experimental diets was either 100% LCTs or 95% triacetin/5% LCTs. Plasma lactate, glucose, and total ketone body concentrations were not significantly different among dietary treatment groups. Compared with animals fed LCTs and control diet, plasma pyruvate and free fatty acid concentrations were decreased in animals fed triacetin. In contrast, plasma triglyceride concentrations were elevated in animals fed triacetin compared with other groups. Intestinal biochemical measures included total DNA, RNA, protein, and the protein:DNA ratio. Histologic indices measured were villus height in the jejunum and crypt depth in the colon. No significant difference in mucosal protein concentration was observed in the jejunum and colon. Jejunal RNA was significantly decreased in animals fed triacetin compared with other diets. Triacetin feeding significantly increased the DNA content in the jejunum and colon (thereby lowering the protein:DNA ratio), indicating smaller, more numerous cells. Jejunal villus height and colonic crypt depth were not significantly different among dietary treatment groups. Provision of a balanced diet containing 28.5% of the total calories as triacetin had no adverse effects on metabolic substrates and resulted in smaller and more numerous mucosal cells in the jejunum and colon.(ABSTRACT TRUNCATED AT 250 WORDS)

A pertussis toxin-insensitive calcium influx mediated by neuropeptide Y2 receptors in a human neuroblastoma cell line

Stimulation of neuropeptide Y (NPY) Y2 receptors induced an intracellular free Ca2+ ([Ca2+]i) increase in a human neuroblastoma cell line, CHP-234. When NPY in a Ca(2+)-free solution was applied, this increase was abolished. Depolarization with high KCl evoked no response, suggesting that the responses were not mediated by voltage-gated Ca2+ channels. There was no evidence that the NPY response consisted of a capacitative Ca2+ entry sensitive to internal Ca2+ store levels. The [Ca2+]i elevation was diminished by Ni2+, a blocker of Ca2+ entry. Mn2+ induced a quench of the fura-2 fluorescence, which ceased promptly upon the removal of NPY, indicating that Ca2+ entry was linked tightly to receptor activation. Although thapsigargin- and ryanodine-sensitive Ca2+ stores were present, NPY-induced responses were not impaired by pretreatment with either drug. Furthermore, NPY had no effect on the thapsigargin-sensitive store. Pertussis toxin did not affect the NPY-stimulated [Ca2+]i increase, although it abolished the NPY-dependent inhibition of cAMP production. It is concluded that the Y2 receptors couple directly to receptor-operated Ca2+ channels without the involvement of intracellular Ca2+ stores. The results also indicate that Y2 receptors can activate both pertussis toxin-sensitive and -insensitive mechanisms in the same cell.

Childhood and adult socioeconomic status as predictors of mortality in Finland

Research has suggested that social-class differences in adult health may be at least partly determined by conditions earlier in life. In 2636 Finnish men, we assessed impact of childhood and adult socioeconomic conditions on adult mortality risk by examining whether differing socioeconomic life-courses from early childhood to adulthood were associated with different risks of all-cause and cardiovascular mortality. Compared with high-income adults, those with low income had increased relative risks of all-cause (2.54, 95% CI 1.83-3.53) and cardiovascular (2.37, 1.51-3.7) mortality, but these increased risks were not related in either adult group to childhood socioeconomic conditions. Men who went from low-income childhood to high-income adulthood had the same mortality risks as those whose socioeconomic circumstances were good in both childhood and adulthood (1.14, 0.56-2.31, all causes; 0.99, 0.39-2.51, cardiovascular). By contrast, men who experienced poor socioeconomic circumstances as both children and adults were about twice as likely to die as those whose position improved (2.39, 1.28-4.44, all causes; 2.02, 0.9-4.54, cardiovascular). Our findings suggest that socioeconomic conditions in childhood are not important determinants of adult health. We caution against this interpretation--a life-course approach to socioeconomic differences in adult health requires understanding of the social and economic context in which individual life-courses are determined.

Cyclic nucleotide-gated channels of rat olfactory receptor cells: divalent cations control the sensitivity to cAMP

cAMP-gated channels were studied in inside-out membrane patches excised from the apical cellular pole of isolated olfactory receptor cells of the rat. In the absence of divalent cations the dose-response curve of activation of patch current by cAMP had a KM of 4.0 microM at -50 mV and of 2.5 microM at +50 mV. However, addition of 0.2 or 0.5 mM Ca2+ shifted the KM of cAMP reversibly to the higher cAMP concentrations of 33 or 90 microM, respectively, at -50 mV. Among divalent cations, the relative potency for inducing cAMP affinity shifts was: Ca2+ > Sr2+ > Mn2+ > Ba2+ > Mg2+, of which Mg2+ (up to 3 mM) did not shift the KM at all. This potency sequence corresponds closely to that required for the activation of calmodulin. However, the Ca(2+)-sensitivity is lower than expected for a calmodulin-mediated action. Brief (60 s) transient exposure to 3 mM Mg2+, in the absence of other divalent cations, had a protective effect in that following washout of Mg2+, subsequent exposure to 0.2 mM Ca2+ no longer caused affinity shifts. This protection effect did not occur in intact cells and was probably a consequence of patch excision, possibly representing ablation of a regulatory protein from the channel cyclic nucleotide binding site. Thus, the binding of divalent cations, probably via a regulatory protein, controls the sensitivity of the cAMP-gated channels to cAMP. The influx of Ca2+ through these channels during the odorant response may rise to a sufficiently high concentration at the intracellular membrane surface to contribute to the desensitization of the odorant-induced response. The results also indicate that divalent cation effects on cyclic nucleotide-gated channels may depend on the sequence of pre-exposure to other divalent cations.

Properties of cyclic nucleotide-gated channels mediating olfactory transduction. Activation, selectivity, and blockage

Cyclic nucleotide-gated channels (cng channels) in the sensory membrane of olfactory receptor cells, activated after the odorant-induced increase of cytosolic cAMP concentration, conduct the receptor current that elicits electrical excitation of the receptor neurons. We investigated properties of cng channels from frog and rat using inside-out and outside-out membrane patches excised from isolated olfactory receptor cells. Channels were activated by cAMP and cGMP with activation constants of 2.5-4.0 microM for cAMP and 1.0-1.8 for cGMP. Hill coefficients of dose-response curves were 1.4-1.8, indicating cooperativity of ligand binding. Selectivity for monovalent alkali cations and the Na/Li mole-fraction behavior identified the channel as a nonselective cation channel, having a cation-binding site of high field strength in the pore. Cytosolic pH effects suggest the presence of an additional titratable group which, when protonated, inhibits the cAMP-induced current with an apparent pK of 5.0-5.2. The pH effects were not voltage dependent. Several blockers of Ca2+ channels also blocked olfactory cng channels. Amiloride, D 600, and diltiazem inhibited the cAMP-induced current from the cytosolic side. Inhibition constants were voltage dependent with values of, respectively, 0.1, 0.3, and 1 mM at -60 mV, and 0.03, 0.02, and 0.2 mM at +60 mV. Our results suggest functional similarity between frog and rat cng channels, as well as marked differences to cng channels from photoreceptors and other tissues.

Prognostic implications of evaluation for lymph node involvement by T-cell antigen receptor gene rearrangement in mycosis fungoides

We investigated the correlation between the detection of clonal rearrangement of the T-cell antigen receptor gene (TCRR) in lymph node tissue with histopathologic lymph node classification in 33 patients with mycosis fungoides with and without the Sezary Syndrome. We analyzed DNA extracted from lymph nodes that were histologically uninvolved (LN1-2), dermatopathic nodes with clusters of atypical cells (LN3), and nodes effaced with lymphoma (LN4) and found TCRR in none of five LN1-2 nodes, 8 of 17 LN3 nodes, and 10 of 11 LN4 nodes. Further, the detection of TCRR correlated with presence of palpable adenopathy (P2 less than .0001) and was associated with a worse survival (P2 = .0024). Within the subgroup of patients with LN3 nodes, there was a trend (P2 = .14) toward inferior survival if nodes were involved by TCRR, irrespective of extent of skin disease. We conclude that detection of TCRR in nodes from mycosis fungoides patients is an objective and reliable means of assessing tumor infiltration of lymph node and is associated with an inferior survival.

An analysis of Na+ currents in rat olfactory receptor neurons

Na+ currents were observed in acutely-dissociated adult rat olfactory receptor neurons using the whole-cell recording techniques. The threshold for current activation was near -70 mV and currents were fully activated by -10 mV (midpoint: -45 mV). Steady-state inactivation was complete at potentials more positive than -70 mV and half complete at -110 mV (+/- less than 1, n = 8). Complete recovery from inactivation required one second at -100 mV (n = 7). The addition of 10 microM tetrodotoxin or 1 mM Zn2+ to the external solution was required to completely block the current. The current differs from those in amphibian and cultured neonatal rat olfactory neurons in its unusually negative voltage-dependence and slow recovery. Since mammalian olfactory neurons have very high input resistances, physiological resting potentials cannot usually be measured using whole-cell recording techniques. However, predominantly-capacitatively-coupled spikes activated by depolarisation were frequently observed in cell-attached patches. This indicates that the cells were excitable and implies that they must have had resting potentials more negative than -90 mV in order for this current to underlie the action potential.

Slowly activating K+ channels in rat olfactory receptor neurons

Patch-clamp techniques were used to investigate slowly activating, Ca(2+)-insensitive K+ channels of isolated rat olfactory receptor neurons. These channels had a unitary conductance of 135 pS and were only found in a small proportion (less than 5%) of membrane patches. Upon depolarization to voltages more positive than -50 mV, the channels activated gradually over a period of at least 10 s. When hyperpolarized to negative voltages, channel activity deactivated in a slow but voltage-dependent manner. These channels may underlie a slowly activating K+ current that is observed in approximately 30% of whole-cell recordings. Similar single channels have been reported in smooth muscle cells, but this is the first demonstration of these channels in any type of neuron. The channels may contribute to the spike frequency adaptation and post-stimulus hyperpolarization that are observed during the excitatory response to odorants. They may also contribute to cell repolarization following large odorant-stimulated receptor currents.