Bone mineral density and risk of breast cancer: differences by family history of breast cancer. Study of Osteoporotic Fractures Research Group

Recent studies have suggested that bone mineral density (BMD) is related to risk of breast cancer in elderly women. This study investigated whether the level of breast cancer risk associated with BMD in women with a positive family history of breast cancer is different from that in women without a family history of breast cancer. Radial and calcaneus BMD were measured at baseline (1986-1988) in 7,250 elderly white women enrolled in the Study of Osteoporotic Fractures, and initial breast cancer status was ascertained at year 1 of follow-up. After a mean of 3.2 years of additional follow-up, 104 incident breast cancer cases, 20 of which appeared in women with a family history of breast cancer, were identified and confirmed by medical record review. Modification of the BMD effect by family history status was assessed by inclusion of interaction terms in proportional hazards regression models. Among women without a family history of breast cancer, those with a proximal radius BMD in the highest tertile were at a 1.48-fold increased risk compared with women in the lowest tertile; among women with a positive family history of breast cancer, those with highest tertile BMD were at a 3.41-fold increased risk compared with women in the lowest tertile. These results suggest that the association between BMD and breast cancer may be different in subgroups of women defined by family history.

A release mechanism for stored ATP in ocular ciliary epithelial cells

Purines can modify ciliary epithelial secretion of aqueous humor into the eye. The source of the purinergic agonists acting in the ciliary epithelium, as in many epithelial tissues, is unknown. We found that the fluorescent ATP marker quinacrine stained rabbit and bovine ciliary epithelia but not the nerve fibers in the ciliary bodies. Cultured bovine pigmented and nonpigmented ciliary epithelial cells also stained intensely when incubated with quinacrine. Hypotonic stimulation of cultured epithelial cells increased the extracellular ATP concentration by 3-fold; this measurement underestimates actual release as the cells also displayed ecto-ATPase activity. The hypotonically triggered increase in ATP was inhibited by the Cl--channel blocker 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) in both cell types. In contrast, the P-glycoprotein inhibitors tamoxifen and verapamil and the cystic fibrosis transmembrane conductance regulator (CFTR) blockers glybenclamide and diphenylamine-2-carboxylate did not affect ATP release from either cell type. This pharmacological profile suggests that ATP release is not restricted to P-glycoprotein or the cystic fibrosis transmembrane conductance regulator, but can proceed through a route sensitive to NPPB. ATP release also was triggered by ionomycin through a different NPPB-insensitive mechanism, inhibitable by the calcium/calmodulin-activated kinase II inhibitor KN-62. Thus, both layers of the ciliary epithelium store and release ATP, and purines likely modulate aqueous humor flow by paracrine and/or autocrine mechanisms within the two cell layers of this epithelium.

Induction of axial eye elongation and myopic refractive shift in one-year-old chickens

Depriving the eyes of neonatal animals of form vision induces axial eye elongation and ipsilateral myopia. We studied one-year-old chickens, an age at which full body growth has been attained, to learn if form deprivation myopia can develop at a later stage. We found that ocular reactivity to visual form deprivation continues in one-year-old chickens; but both the growth stimulation and the myopic shift in refraction are attenuated compared with newly hatched birds. Neurochemical changes in visually deprived eyes of one-year-old chickens parallel those in newly hatched chicks: ipsilateral decreases in retinal dopamine and in the activity of ciliary ganglion and uveal choline acetyltransferase. These findings strengthen the relevance of the form deprivation model to more common human myopia and suggest a common eye growth control mechanism at both ages.

Fenoldopam, a selective dopamine-1 receptor agonist, raises intraocular pressure in males with normal intraocular pressure

Recent studies have suggested that intravenous infusion of fenoldopam, a selective dopamine-1 receptor agonist, elevates intraocular pressure (IOP) in man. This study evaluated the effect of intravenous fenoldopam on IOP, aqueous humor outflow facility and gonioscopy in 12 healthy human subjects. Three doses (0.2, 0.5 and 1.0 microg/kg/min) were infused for 120 minutes in a double masked, placebo controlled, four-way crossover design. IOP was measured every 20 minutes in the supine position and every 40 minutes while sitting during the drug and placebo infusions. Tonography and gonioscopy were performed at baseline and after 120 minutes of infusion. Compared to placebo, IOP increased by 3.5 mm Hg (32%) for the lowest dose, 5.8 mm Hg (46%) for the intermediate dose, and 6.9 mm Hg (55%) for the highest dose (p<0.05 for all three doses). IOP returned to baseline within 30 minutes of stopping the infusion. The outflow facility decreased from baseline by 26% after 120 minutes of infusion for all drug doses. In contrast, outflow facility increased from baseline by 11% during placebo infusion. Compared to placebo, the fenoldopam induced changes in outflow were statistically significant (p<0.05). There was no change in the gonioscopic appearance of the anterior chamber angle during the infusion. This study shows that systemic administration of a selective dopamine-1 receptor agonist causes a significant dose-dependent increase in IOP that can be explained in part by diminished outflow facility. These results support a role for the dopamine-1 receptor in the modulation of IOP in general and suggest modulation of aqueous humor outflow by dopaminergic receptors.

OCMAP-PLUS: a program for the comprehensive analysis of occupational cohort data

The Occupational Cohort Mortality Analysis Program (OCMAP) has been redesigned for optimal microcomputer use and extended to include new computing algorithms. The new program, OCMAP-PLUS, offers a comprehensive, flexible, and efficient analysis of incidence or mortality rates and standardized measures in relation to multiple and diverse work history and exposure measures. New features include executable code, minimization of memory requirements, disk file storage of person-day arrays, stratified analyses by geographic area, employment status and up to eight exposure variables, a data imputation algorithm for study members with unknown race, and enhanced algorithms for constructing several time-dependent exposure measures. New modules create grouped data files for Poisson and logistic regression and risk set files for use in relative risk regression analysis. The Mortality and Population Data System (MPDS) provides external comparison rates and proportional mortalities. Analysis from two recent cohort mortality studies illustrate several new features.

Ocular axial length and choroidal thickness in newly hatched chicks and one-year-old chickens fluctuate in a diurnal pattern that is influenced by visual experience and intraocular pressure changes

Low coherence laser Doppler interferometry (LDI) allows high precision measurements of the axial length of the eye and of the thickness of the individual layers of the ocular fundus. Here, we used LDI to monitor diurnal changes in these dimensions in eyes of newly hatched chicks and one-year-old chickens with normal or altered visual input. In chicks and chickens with normal visual experience, axial eye length displays diurnal fluctuations increasing during the light phase. Choroidal thickness also exhibits a diurnal pattern, shrinking during the day and expanding during the night. Retinal thickness does not vary. Based on the pressure compliance of the enucleated chick eye, the diurnal intraocular pressure (IOP) fluctuation could contribute both to the increase in axial length and to daytime choroidal shrinkage. Following deprivation of form vision by unilateral goggle wear, occluded chick eyes demonstrate enhanced axial elongation. Diurnal fluctuations in axial length but not in choroidal thickness are temporarily disrupted. The retina of form deprived eyes thins approximately 10% in five days. In contralateral eyes, the diurnal patterns of both axial length and choroidal thickness fluctuations are also disrupted. Following occluder removal in chicks, choroidal thickness increases for several days during both the light and dark phase, leading to its overall expansion. Retinal thickness returns to baseline. When deprived of form vision for five days, the eyes of year-old chickens do not exhibit measurable axial elongation. Diurnal patterns of fluctuation in axial length and choroidal thickness are however disrupted. After goggle removal, axial length fluctuation is restored to normal, but the diurnal choroidal thickness pattern is inverted. In contralateral eyes, choroidal thickness exhibits normal diurnal fluctuations both during and after form vision deprivation. In conclusion, axial length and choroidal thickness fluctuations are influenced by visual experience in both newborn chicks and one-year-old chickens. In selected instances a binocular interaction regarding axial length and choroidal thickness changes is suggested, the effect weakening with age.

Neuropeptide Y-like immunoreactivity localizes to preganglionic axon terminals in the rhesus monkey ciliary ganglion

PURPOSE

To characterize neuropeptide distribution in the ciliary ganglion of rhesus monkeys (Macaca mulatta).

METHODS

Cryostat tissue sections of fixed rhesus monkey ciliary, pterygopalatine, superior cervical, and trigeminal ganglia were incubated with antisera to neuropeptide Y (NPY), calcitonin gene-related peptide (CGRP), substance P (SP), vasoactive intestinal peptide (VIP), tyrosine hydroxylase (TH), and dopamine-beta-hydroxylase (DBH). Antibody binding was visualized by indirect immunofluorescence.

RESULTS

NPY-like immunoreactive (LI) nerve terminals surrounded 80% of ciliary ganglion cells, but ciliary ganglion cell somata were unstained. NPY-LI cells were present in the superior cervical ganglion, in which almost all cells were TH- and DBH-LI, and in the pterygopalatine ganglion, in which almost all cells were VIP-LI. Because neither TH, DBH, nor VIP immunoreactivity was detected in nerves contacting ciliary ganglion cells, the NPY-LI input to ciliary neurons does not likely derive from the autonomic ganglia. The trigeminal ganglion, another potential source, had no NPY-LI neurons. CGRP- and SP-LI axons from the nasociliary nerve traversed the ciliary ganglion; a small number of varicose axons were distributed among ganglion cells and rarely surrounded cell somata. Most ciliary ganglion cells were TH-LI, but only a few were DBH-LI.

CONCLUSIONS

Based on these patterns of peptide immunoreactivities, the NPY-LI nerve fibers investing ciliary ganglion cells in the rhesus monkey are most likely preganglionic axon terminals of mesencephalic parasympathetic neurons. Although the origin and function of these NPY-LI nerves remains to be established, the present finding adds to the remarkable diversity of neuropeptide immunoreactivity so far identified in preganglionic and postganglionic cells of the ciliary ganglion in different species of birds and mammals, including primates.

A case-control study of lung cancer mortality in four rural Arizona smelter towns

To investigate factors related to lung cancer mortality in four Arizona copper-smelter towns, the authors identified 142 lung cancer cases and 2 matched controls per case from decedent residents during 1979-1990. The authors obtained detailed information on lifetime residential, occupational, and smoking histories via structured telephone interviews with knowledgeable informants. The authors linked estimated historical environmental exposures to smelter emissions (based on atmospheric diffusion modeling of measured sulfur dioxide concentrations) with residential histories to derive individual profiles of residential exposure. The results of this study provided little evidence of a positive association between lung cancer and residential exposure to smelter emissions. Conditional logistic regression analysis revealed a statistically significant positive association between lung cancer and reported employment in copper mines and/or smelters, although specific factors associated with the apparently increased risk among these workers could not be identified in this community-based study.

A case-control study of lung cancer mortality in six Gila Basin, Arizona smelter towns

To investigate factors related to lung cancer mortality in six Arizona copper smelter towns, we identified 185 lung cancer cases and two matched controls per case from decedent residents during 1979-1990. Detailed information on lifetime residential, occupational, and smoking history was obtained by structured telephone interviews with knowledgeable informants. Interviews were completed for 82% of 183 eligible cases and 88% of the targeted number (366) of controls. Estimated historical environmental exposures to smelter emissions, based on atmospheric diffusion modeling of measured SO2 concentrations, were linked with residential histories to derive individual profiles of residential exposure. Occupational histories were characterized by potential exposure to smelter emissions, asbestos, and ionizing radiation. Conditional logistic regression was used to compare study factors in cases and controls with adjustment for potential confounding factors: gender, Hispanic ethnicity, and smoking. In overall and gender-specific analyses, no statistically significant associations were observed between lung cancer risk and any of the measures of residential exposure to smelter emissions considered (town of residence at time of death, highest level of exposure, and duration or cumulative exposure above background levels), or any of the estimated occupational exposures (definite or potential asbestos, potential ionizing radiation, definite or potential smelter). Among male residents of some, but not all, towns, there was some evidence of a positive association between lung cancer risk and reported copper smelter-related employment (reported as definite), with the highest risk observed for Miami, Arizona. This study provided little evidence of a positive association between lung cancer mortality and residential exposure to smelter emissions. Specific factors associated with the apparent heterogeneity in lung cancer risk across study towns cannot be identified in this community-based study.

Effect of 5-HT1A receptor agonist, 8-OH-DPAT, on cough responses in the conscious guinea pig

We have studied the role for 5-hydroxytryptamine (5-HT) in the modulation of the cough reflex by examining the effect of a selective 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) on cough and respiratory rate in conscious guinea pigs. Animals were placed in a box and exposed to the tussive agent citric acid (0.5 M) for 10 min, 3 min after terbutaline (0.05 mg/kg i.p.) was administered to prevent bronchoconstriction. 8-OH-DPAT inhibited at low doses (0.008 and 0.016 mg/kg) but potentiated at high doses (0.25 and 0.5 mg/kg) the citric acid-induced number of coughs, but dose-dependently increased respiratory rate. Methysergide (0.05-5 mg/kg), a 5HT1 and 5HT2 receptor antagonist, and ketanserin (0.005 mg/kg), a 5HT2 receptor antagonist, had no effects on cough or respiratory rate. Methysergide inhibited the increased cough responses and respiratory rate induced by 8-OH-DPAT at high doses, while ketanserin was without effect. These results suggest that 8-OH-DPAT may induce both in inhibition and activation of the cough reflex, the latter involving central 5HT1-receptor activation.

Medical outcomes and antimicrobial costs with the use of the American Thoracic Society guidelines for outpatients with community-acquired pneumonia

CONTEXT

The American Thoracic Society (ATS) published guidelines based on expert opinion and published data--but not clinically derived or validated--for treating adult outpatients with community-acquired pneumonia.

OBJECTIVE

To compare medical outcomes and antimicrobial costs for patients whose antimicrobial therapy was consistent or inconsistent with ATS guidelines.

DESIGN

Multicenter, prospective cohort study.

SETTING

Emergency departments, medical clinics, and practitioner offices affiliated with 3 university hospitals, 1 community teaching hospital, and 1 health maintenance organization.

PARTICIPANTS

A total of 864 immunocompetent, adult outpatients with community-acquired pneumonia: 546 aged 60 years or younger with no comorbidity and 318 older than 60 years or with 1 comorbidity or more.

MAIN OUTCOME MEASURES

Patients' antimicrobial therapy was classified as being consistent or inconsistent with the ATS guidelines. Mortality, subsequent hospitalization, medical complications, symptom resolution, return to work and usual activities, health-related quality of life, and antimicrobial costs were compared among those treated consistently or inconsistently with the guidelines.

RESULTS

Outpatients aged 60 years or younger with no comorbidity who were prescribed therapy consistent with ATS guidelines (ie, erythromycin with some exceptions) had 3-fold lower antimicrobial costs ($5.43 vs $18.51; P<.001) and no significant differences in medical outcomes. Outpatients older than 60 years or with 1 comorbidity or more who were prescribed therapy consistent with ATS guidelines (ie, second-generation cephalosporin, sulfamethoxazole-trimethoprim, or beta-lactam and beta-lactamase inhibitor with or without a macrolide) had 10-fold higher antimicrobial costs ($73.50 vs $7.50; P<.001); despite trends toward higher mortality and subsequent hospitalization, no significant differences in medical outcomes were observed.

CONCLUSION

Our findings support the use of erythromycin as recommended by the ATS guidelines for outpatients aged 60 years or younger with no comorbidity. Although the antimicrobial therapy recommended in outpatients older than 60 years or with 1 comorbidity or more is more costly, this observational study provides no evidence of improved medical outcomes in the small subgroup who received ATS guideline-recommended therapy.

Retinal dopamine in the recovery from experimental myopia

PURPOSE

To address further a possible role for retinal dopamine in postnatal eye growth, we studied the response of retinal dopamine in eyes of chicks recovering from myopia.

METHODS

Newborn chicks either received a unilateral translucent goggle to induce form deprivation myopia or were reared with unimpaired visual input. The goggle was removed from half of the chicks on day 7. Myopic, recovering and control never-goggled chicks were studied on days 7, 9 and 14. Eyes were enucleated postmortem and measured in axial and equatorial dimensions with calipers. Retinal levels of dopamine and its principal metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) were assayed by high performance liquid chromatography with electrochemical detection.

RESULTS

Compared to contralateral and control eyes, retinas of goggled eyes at each time point had reduced levels of dopamine and DOPAC and a lowered calculated DOPAC/dopamine ratio, an index of dopamine metabolism. In eyes recovering from myopia, all biochemical parameters showed prominent increases by 2 days after goggle removal and had reached the level of both contralateral eyes and control eyes by one week after goggle removal. As evidence of a contralateral effect, the retinas of open eyes of chicks wearing a unilateral goggle demonstrated equal dopamine levels but reduced DOPAC compared to eyes of never-goggled chicks.

CONCLUSION

An early rise and eventual normalization of retinal dopamine, DOPAC and the DOPAC/dopamine ratio correlate with recovery from myopia. Combined with recent results from lens rearing experiments, these findings suggest that dopaminergic amacrine cells may participate in visually guided eye growth regulation and not just in the myopia response to visual form deprivation. The retinal biochemical alteration in eyes contralateral to a goggle identifies a previously unappreciated binocular interaction in the chick.

The hospital discharge decision for patients with community-acquired pneumonia. Results from the Pneumonia Patient Outcomes Research Team cohort study

BACKGROUND

The hospital discharge decision directly influences the length of stay in patients with community-acquired pneumonia, yet no information exists on how physicians make this decision.

OBJECTIVES

To identify the factors physicians considered the factors responsible for extending length of hospital stay in clinically stable patients, and the outpatient medical services that would allow earlier hospital discharge for patients with community-acquired pneumonia.

METHODS

Physicians responsible for the hospital discharge decision of patients with community-acquired pneumonia were asked to identify the factors responsible for extending stay in patients hospitalized beyond stability, and the medical services that could have allowed earlier hospital discharge to occur.

RESULTS

For the 418 eligible patients with community-acquired pneumonia identified during the study, 332 questionnaires (79%) were completed by 168 physicians. Physicians believed 71 patients (22%) were discharged from the hospital 1 day or more (median, 2.5 days) after reaching clinical stability. The most common factors rated as being "very important" in delaying discharge were diagnostic evaluation or treatment of comorbid illness (56%), completion of a "standard course" of antimicrobials (15%), and delays with arrangements for long-term care (14%). Among the 302 patients with available information on both length of hospital stay and stability at discharge, median length of stay was 7.0 days for the 29 low-risk patients hospitalized beyond reaching clinical stability and 5.0 days for the remaining 128 low-risk patients (P < .005); median length of stay was 12.5 days for the 42 medium- and high-risk patients hospitalized beyond reaching clinical stability and 8.0 days in the remaining 113 medium- and high-risk patients (P < .001). Frequently cited medical services that "probably" or "definitely" would have allowed earlier discharge to occur included availability of home intravenous antimicrobial infusion (26%) and home visits by nurses (20%).

CONCLUSIONS

Physicians believed that diagnostic evaluation or treatment of comorbid illness, completion of a standard course of antimicrobial therapy, and delays with arrangements for long-term care delayed hospital discharge in clinically stable patients. Addressing the efficiency of these aspects of inpatient medical care, as well as providing home treatment programs, could decrease the length of hospital stay in patients with community-acquired pneumonia.

Mortality among chemical workers in a factory where formaldehyde was used

OBJECTIVES

An independent and updated historical cohort mortality study was conducted among chemical plant workers to investigate further an association between exposures to formaldehyde and particulates and cancers of the nasopharynx and lung reported in an earlier National Cancer Institute study of the same plant.

METHODS

Subjects were 7359 workers who were first employed between 1941 and 1984 in a factory in Wallingford, Connecticut where formaldehyde was used. Vital status was determined on 31 December 1984 for 96% of the cohort and death certificates were obtained for 93% of 1531 known deaths. Exposures of individual workers were estimated quantitatively for formaldehyde, product particulates, and non-product particulates, and qualitatively for pigment. Statistical analyses focused on 6039 white men in 1945-84. Cohort data that could not have been included in the National Cancer Institute study were also analysed separately.

RESULTS

Mortality among long term workers (employed > or = 1 y) was generally similar to or more favourable than that of the general population, and there was little evidence of a relation between either rates of lung cancer or standardised mortality ratios (SMRs) and several measures of exposure to formaldehyde, particulates, and pigment. For several causes including lung cancer, death rates among short term workers (employed < 1 y) were significantly increased. Short term workers did not seem to differ from long term workers for the exposures considered. Among all white men, a significant SMR of 550 (local comparison) for nasopharyngeal cancer (NPC) was based on the same four index cases identified in the earlier study of this plant. Only one case of nasopharyngeal cancer had any appreciable exposure to formaldehyde. No new cases of nasopharyngeal cancers were found among the cohort data that could not have been included in the National Cancer Institute study--that is, extended observation time and additional study members.

CONCLUSIONS

Among workers employed for at least one year, this study provides little evidence that the risk of lung cancer is associated with exposure to formaldehyde alone or in combination with particulates or pigment. The significant increases in both the rates and SMRs for lung cancer seem to be primarily a phenomenon of short term workers, but the possibility remains that unmeasured occupational or non-occupational factors may have played a part.

Measurement by laser Doppler interferometry of intraocular distances in humans and chicks with a precision of better than ±20 µm

A laser Doppler interferometer was built for the precise measurement of intraocular optical distances in humans and chicks. A technique using Purkinje images was developed to position the chick's eye reproducibly. A computer algorithm for the objective analysis of the interference signal and determination of the optical distances is presented. The precision of this noncontact interferometric method for measuring the cornea-retina distance is better than ±20 µm.

Validation of laser Doppler interferometric measurements in vivo of axial eye length and thickness of fundus layers in chicks

Purpose. Laser Doppler interferometry (LDI) permits the measurement of intraocular distances to a precision of better than 20 microm. The signal complex from the posterior segment of the eye consists of four peaks in the chick, an animal frequently used in ocular development studies. The present study sought to identify anatomical landmarks corresponding to these LDI peaks. Methods. Distances obtained with LDI at the posterior pole were compared to axial length components measured with three independent methods: vernier calipers, tissue sections and high frequency A-scan ultrasound. Results. LDI reflections appear to originate from the retinal inner limiting membrane, Bruch's membrane and the inner and outer scleral surfaces. Conclusions. The non-invasive and highly precise nature of LDI measurements enables repetitive and accurate assessment of intraocular distances. Such measurements should prove particularly useful for the assessment of short-term cyclic variations in intraocular distances as well as post-natal eye growth.

The ciliary ganglion and vitreous cavity shape

PURPOSE

To learn the influence of the ciliary ganglion on the postnatal growth of eyes with unimpaired visual input and of eyes beneath an image diffusing goggle.

METHODS

Newborn chicks received unilateral ciliary ganglionectomy or unilateral sham operation and were reared either with or without a goggle ipsilateral to the surgical procedure. Ocular refractions and ultrasound measurements were made on anesthetized chicks; eyes enucleated postmortem were measured in axial and equatorial dimensions with calipers and studied histologically.

RESULTS

Excessive growth of open eyes in the equatorial dimensions followed ciliary ganglionectomy and became more pronounced as the chicks grew older. There was only a modest increase in axial growth. Ganglionectomy also induced relative hyperopia; lens thinning contributed to this effect and likely was a direct result of disrupted parasympathetic input to the ciliary muscle. Ganglionectomy also slightly increased the thickness of the choroid in the posterior pole but not in more peripheral locations.

CONCLUSION

We conclude that the ciliary ganglion exerts an inhibitory influence on the postnatal growth of open eyes; the main effect is in the equatorial dimension of the vitreous cavity, with a smaller effect on axial length. Ciliary ganglionectomy exerted minimal influence on the development of experimental myopia, known to be induced by the goggle regimen. The amount of equatorial expansion in goggle-induced myopia was greater than after ganglionectomy alone, indicating that other factors besides the ciliary ganglion can influence the equatorial dimension of the vitreous cavity.

Peptidergic innervation of the primate meibomian gland

PURPOSE

To localize and characterize nerves in primate meibomian glands using immunohistochemical staining for neuropeptides and neuronal enzymes.

METHODS

Upper eyelids were obtained from seven rhesus monkeys (Macaca mulatta) and one cynomolgous monkey (Macaca fascicularis). The tissues were fixed either by immersion in Zamboni's fixative or by transcardiac perfusion with paraformaldehyde and glutaraldehyde and were then postfixed. Cryostat tissue sections of the lids were stained by immunohistochemistry using rabbit antisera to neuron-specific enolase (NSE), tyrosine hydroxylase (TH), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), calcitonin gene-related peptide (CGRP), and substance P (SP), followed by a fluorescence visualization system.

RESULTS

Used as a marker for the overall nerve distribution, NSE antibodies revealed abundant smooth and varicose nerve fibers closely apposed to the basement membranes of acini of the meibomian glands. Numerous nerve fibers near the meibomian gland acini were immunoreactive for NPY and VIP, but nerve fibers containing TH, CGRP, and SP were more sparse in the meibomian glands. Nerve fibers also were visualized in other eyelid structures, including conjunctiva, epidermis, hair follicles, and subconjunctival lymphoid follicles.

CONCLUSIONS

The meibomian glands of rhesus and cynomolgous monkeys are richly innervated by diverse nerve fiber types. The immunohistochemical staining suggests a largely parasympathetic origin for this innervation, with relatively smaller contributions from sympathetic and sensory sources. These findings also suggest that meibomian gland secretion is under the control of diverse neurotransmitter-neuromodulator mechanisms.

Sex differences in chick eye growth and experimental myopia

Stimulated by reported sex differences in eye size and refraction in humans, we compared refractions and ocular size measurements of male and female chicks. Chicks were reared under a 12-hr light/dark cycle with one eye open and the other occluded by a goggle or lid suture, each well-established means of inducing ipsilateral myopia. While the open eyes of the two sexes emmetropized equally well, both ultrasound and caliper measurements demonstrated that on average males have larger eyes. Although statistically significant for defined populations, the sex differences in open eyes were to small to be diagnostic for individual birds. The visually-deprived eyes of male chicks were more reactive than those of females, especially following deprivation by a goggle. Consistently, the anterior chamber of visually-deprived eyes of males was deeper than those of the females regardless of the means of impairing vision. With a goggle, males also developed more myopia and a deeper vitreous chamber than females similarly occluded. When goggles were removed, rapid recovery occurred in 2 weeks irrespectively of sex.

Nitric oxide synthase in autonomic innervation of the cat carotid body

In the cat carotid body, nitric oxide synthase (NOS) immunoreactivity and NADPH diaphorase activity localize in nerve fibers mainly associated with blood vessels and occasionally lying close to glomus cells. The NOS-positive innervation originates in part from multipolar ganglion cells scattered in and around the carotid body and in the glossopharyngeal nerve. In the superior cervical ganglion, NOS and diaphorase staining localizes to many preganglionic axons and also to a small population of vasoactive intestinal peptide-positive, presumably cholinergic, ganglion cells. Positively stained ganglion cells are absent in the petrosal ganglion and very rare in the nodose ganglion, although both sensory ganglia display characteristic distributions of cells immunoreactive for calcitonin gene-related peptide, substance P and tyrosine hydroxylase. The NOS-positive innervation of the carotid body thus appears to be autonomic, originating mainly from a population of dispersed ganglion cells, and probably parasympathetic in nature. The superior cervical ganglion also may supply some pre- or postganglionic NOS-positive axons. Nitric oxide released from these nerves could affect glomus cell activity directly or indirectly by vasoregulation.

Comparison of a disease-specific and a generic severity of illness measure for patients with community-acquired pneumonia

OBJECTIVE

To compare the performances of a disease-specific severity of illness index and a prototypical generic severity of illness measure, MedisGroups Admission Severity Groups (ASGs), for patients with community-acquired pneumonia.

DESIGN

A retrospective database study.

PATIENTS

Adult patients (aged > or = 18 years) with an ICD-9-CM principal diagnosis of pneumonia in 78 MedisGroups Comparative Database hospitals.

METHODS

The pneumonia severity of illness index (PSI) was developed to predict hospital mortality using logistic regression analyses in a 70% random sample of study patients. The performances of the PSI and the generic severity measure were assessed among the remaining 30% of patients by comparing observed mortalities within the five PSI and ASG severity classes, and areas under their receiver operating characteristic (ROC) curves. Both the PSI and the generic severity measure were used to estimate the 95% confidence interval of the expected number of deaths in each of the 78 study hospitals. Hospitals with an observed number of deaths outside these limits were identified as outliers.

RESULTS

There were 14,199 study patients who had community-acquired pneumonia, and 1,542 (10.9%) died during hospitalization. In comparison with the generic severity measure, the PSI more accurately identified patients at extremely low risk of death, and had a larger area under its ROC curve (0.84 vs 0.79; p < 0.0001). Of the 78 study hospitals, 17 (21.8%) were classified as outliers for mortality by at least one severity adjustment system. Among the 11 low-outlier hospitals, six were classified by the generic severity measure alone, two by the PSI alone, and three by both systems; among the six high-outlier hospitals, one was classified by the generic measure alone, three by the PSI alone, and two by both systems.

CONCLUSIONS

The PSI provided more accurate estimates of hospital mortality and classified different hospital outliers for mortality than did the generic severity of illness measure for patients with community-acquired pneumonia.

Factitious pheochromocytoma: novel mimickry by Valsalva maneuver and clues to diagnosis

Factitious pheochromocytoma usually occurs in patients surreptitiously ingesting adrenergic medications. We encountered a case of factitious pheochromocytoma where in the subject mimicked hemodynamic (profound hypertension) and biochemical (plasma catecholamine elevation) manifestations of the illness by consciously altering autonomic function with Valsalva maneuver. Clues to this presentation included visible performance of Valsalva maneuver, marked disparity between blood pressures recorded in the presence and absence of the subject's knowledge, normal urinary catecholamine and metabolite excretion, and normal plasma chromogranin A. We reproduced, in part, the hemodynamic and biochemical manifestations of this presentation with Valsalva maneuver in healthy subjects.

Photoperiod, early post-natal eye growth, and visual deprivation

(1) We studied the influence of photoperiod and unilateral lid suture on post-natal ocular growth in two types of White Leghorn chicks previously reported to respond differently to visual deprivation, Truslow and Cornell K chicks. We analyzed the chicks after 2 weeks of rearing, a time period commonly used in neuropharmacological studies of eye growth but much shorter than in most prior studies of photoperiod effects on the chick eye. (2) Altering the photoperiod length significantly influenced the refraction and growth of both open and sutured eyes even at this early time, with differences between the two types of chicks. (3) The most prominent effect on the open eyes was the development of hyperopia with rearing under constant light, a response especially prominent in the Cornell K chicks. In the open eyes under this condition, the anterior chamber shallowed and the vitreous chamber elongated in the axial dimension only, reciprocal changes that resulted in no net alteration of axial length at 2 weeks. A high variability in refraction of open eyes reared with constant illumination suggests the need for a dark period in the regulation of eye growth. (4) Compared to contralateral open eyes, the lid-sutured eyes of both types of chicks developed longer total axial lengths and enlarged vitreous chambers in both axial and equatorial dimensions under each photoperiod. The effects on anterior chamber depth and refraction were complex and differed between the two types of chicks. (5) The responses in open eyes support the notion that growth of the vitrious chamber of the chick eye is differentially regulated in the axial and equatorial dimensions, previously indicated by pharmacological studies. The responses in both open and sutured eyes indicate different control mechanisms for anterior chamber and vitreous cavity growth.

Propensity score adjustment for pretreatment differences between hospitalized and ambulatory patients with community-acquired pneumonia. Pneumonia Patient Outcomes Research Team (PORT) Investigators

A primary goal of the Pneumonia Patient Outcomes Research Team (PORT) multicenter cohort study is to identify a subgroup of patients with community-acquired pneumonia (CAP) who could be safely treated on an ambulatory basis. The medical outcomes of inpatients and outpatients are to be compared. Propensity score adjustment provides a unified way to control for pretreatment differences in the analysis of all the outcomes in this nonrandomized study by defining "comparable" patients as those with the same propensity score (i.e., the same probability of hospitalization). Data for 747 patients (35.5% hospitalized) with CAP in the Pneumonia PORT study illustrate the development and assessment of a propensity score adjustment. A classification tree algorithm defined seven propensity score strata with hospitalization probabilities ranging from 6.5% to 76.5%. Statistically significant pretreatment imbalances favoring the outpatients were found for 29 of 44 baseline variables considered; after stratification on the propensity score, only 13 of the 29 imbalances remained statistically significant at the 0.05 level. Post hoc stratification on the estimated propensity score consistently reduced, but did not completely eliminate, systematic baseline differences between ambulatory and hospitalized patients with CAP. Regression adjustment can be used in conjunction with propensity score stratification to adjust further for the remaining identified imbalances.

Nitric oxide and choroidal blood flow regulation

PURPOSE

Nitric oxide (NO) has been found to be an endothelial-derived relaxing factor mediating the vasodilatation that results from the stimulation of muscarinic endothelial receptors. It also has been identified as a putative neurotransmitter of parasympathetic origin in choroidal perivascular autonomic fibers. The authors investigated a potential role of NO in choroidal blood flow (ChBF) regulation.

METHODS

Local ChBF in the tapetal region of 26 anesthetized cats was measured by laser Doppler flowmetry. Cats were infused through the femoral vein with increasing dosages of acetylcholine (ACh); N omega-nitro-L-arginine (NNL-A), a specific inhibitor of NO synthesis; L-arginine; and D-arginine. ChBF and mean arterial pressure (MAP) were continuously recorded.

RESULTS

Infusion of 20 micrograms/minute ACh induced a 68% increase in ChBF despite a 9% decrease in MAP. Infusion of 16 mg/minute NNL-A attenuated the ACh-induced increase in ChBF by 46% and increased MAP by 40%. Infusion of different dosages of NNL-A without prior administration of ACh caused ChBF to fall below and MAP to rise above baseline in a dose-dependent fashion. Infusion of L-arginine prior to ACh infusion enhanced by 27% the ACh-induced increase in ChBF, whereas D-arginine had no effect on this increase.

CONCLUSIONS

These findings suggest the presence of a local vasodilatory cholinergic mechanism in the choroid, inducing the release of NO. They also suggest that release of NO in the choroid may maintain basal blood flow to this tissue.

Ciliary ganglion choline acetyltransferase activity in avian macrophthalmos

While present evidence fails to support an etiologic mechanism for myopia based on accommodation or choroidal blood flow, atropine exhibits anti-myopia activity in many species. Accordingly, we studied choline acetyl transferase (ChAT) activity in the ciliary ganglion, uvea and retina of chicks with experimental macrophthalmos to identify a potential pathway for the moderation of eye growth by cholinergic neurons. Following unilateral lid suture or goggle, chicks were reared for 1 week under one of four lighting conditions known to induce macrophthalmos or myopia. Ocular tissues and ciliary ganglia were assayed for ChAT activity by measuring the conversion of 14C-acetyl CoA to 14C-acetylcholine. For some chicks, the goggles were removed at 1 week, and ChAT activity was measured 2 or 7 days later. Depending on the rearing condition, ciliary ganglion ChAT activity was depressed from 16 to 28% ipsilateral to the lid suture; enzyme activity also was reduced in the choroid of visually deprived eyes under most conditions. In contrast, lid suture resulted in no consistent trend in ChAT activity in either the anterior uvea or retina. For chicks wearing a unilateral goggle and reared under a 12:12 hr light/dark cycle, ChAT activity was depressed in the ciliary ganglion, anterior uvea and choroid on the visually deprived side. Following goggle removal to allow recovery from myopia. ChAT activity in the ciliary ganglion and uvea was returned toward that of the control side. The ciliary ganglion may participate in a neural pathway influencing the development of form-deprivation myopia.

Association of intraocular pressure and myopia in children

PURPOSE

While elevated intraocular pressure (IOP) is associated with myopia in adults, its potential influence on the growth of eyes in juveniles without glaucoma is controversial. To address this issue, a possible relation between IOP and refraction in children was sought.

METHODS

A cross-sectional survey of IOP was conducted in children presenting to the Division of Pediatric Ophthalmology at The Children's Hospital of Philadelphia for a complete eye examination. Measurement of IOP was attempted in all children, including those with amblyopia, prematurity, and strabismus. Exclusion criteria were abnormalities of the posterior pole and/or conditions such as cataract that precluded assessment of refractive error. For analysis, myopia was defined as a spherical equivalent of more than 1 diopter (D) of myopia. Logistic regression was used to assess the association between other patient characteristics and presence of myopia.

RESULTS

Intraocular pressure testing was attempted in all age groups, but was more successful in older children. Reliable readings were obtained on 321 subjects. The mean age was 9.8 years, with a mean IOP of 17.3 mmHg in the right eye and 17.2 mmHg in the left and a mean spherical equivalent of +0.2 D in the right eye and +0.1 D in the left. Increasing age, a family history of myopia, and amblyopia were associated myopia. Increasing IOP also was related to myopia. Even when patients with amblyopia, strabismus, and prematurity were exclude, age, family history of myopia, and IOP again were associated with myopia.

CONCLUSIONS

These results indicate that IOP in children may be higher in myopic than nonmyopic eyes. Whether IOP could contribute to the mechanisms causing the abnormal eye growth of childhood myopia requires further study.

Helospectin-like immunoreactivity in the rat eye and pterygopalatine ganglion

Helospectin I and II, nearly identical peptides isolated from lizard venom, show close sequence homology with vasoactive intestinal peptide (VIP). In mammals, the helospectins have been localized immunohistochemically to neurons of the brain, digestive tract and respiratory system, commonly co-existing with VIP. Using an antiserum that recognizes both forms of the peptide, we localized helospectin-like immunoreactivity in the rat eye and pterygopalatine ganglion. In the eye, helospectin-positive nerve fibers were evident mostly in the choroid, associated with small arterial vessels or distributed diffusely in the stroma; they were only occasionally seen in the anterior uvea. All of the helospectin nerve fibers also appeared to be immunoreactive for VIP. In the pterygopalatine ganglion, the principal source of VIP-containing innervation of the posterior uvea, approximately 25% of ganglion cells were helospectin-positive; all helospectin-reactive cells were also strongly positive for VIP. This immunohistochemical localization of helospectin indicates possible involvement in ocular autonomic functions, particularly regulation of blood flow.

Renal hemodynamics in essential hypertension. Racial differences in response to changes in dietary sodium

Previous studies have suggested striking racial differences in hypertension-related renal disease. To explore potential mechanisms responsible for these differences, we investigated changes in renal hemodynamics in white and black essential hypertensive patients in response to alterations in dietary sodium. Patients were untreated, age-matched, and blood pressure-matched white (n = 59) and black (n = 22) males with essential hypertension. Studies were conducted on an inpatient metabolic ward and included assessment of blood pressure, urinary sodium excretion, glomerular filtration rate, renal plasma flow, and renal blood flow after 5 days each of high and low salt diets. In response to high dietary salt intake, both white and black patients demonstrated significantly higher mean arterial pressure, renal plasma flow, and renal blood flow, and there were no racial differences in the changes in these parameters. However, whites and blacks differed significantly in glomerular filtration rate, with black hypertensive patients showing an increase in glomerular filtration rate (+17.3 +/- 5.3 mL/min per 1.73 m2, F = 7.586, P = .007) and white hypertensive patients showing no change (-0.2 +/- 3.3 mL/min per 1.73 m2) in response to high dietary sodium. These data demonstrate racial differences in the autoregulation of glomerular filtration rate in response to changes in dietary sodium. These differences suggest that glomerular hyperfiltration in response to a high salt diet may be a mechanism contributing to the racial disparity in hypertension-related renal disease.

Galanin immunoreactivity in autonomic innervation of the cat eye

In an immunohistochemical study, we find that galanin is much more widely distributed in the peripheral innervation of the cat eye than in other animals so far examined. Previous studies of rat and pig eyes have revealed sparse galanin-positive nerves that presumably originate in the trigeminal ganglion. In contrast, the cat has a rich supply of galanin-containing nerve fibers throughout the uvea. Galanin-positive varicose nerves concentrate densely in iris muscles and distribute more sparsely in the ciliary muscle. The ciliary processes have a plexus of galanin-positive nerves underlying the ciliary epithelium at their base and positive nerve fibers coursing within their stroma. The ciliary artery and its branch vessels in the uvea are invested with a dense plexus of galanin-positive nerves. All autonomic ganglia supplying the eye contain cells that express galanin. It is present in 97% of superior cervical ganglion cells, coexisting with both tyrosine hydroxylase and neuropeptide Y; in 80% of pterygopalatine ganglion cells, most of which also contain vasoactive intestinal peptide; and in approximately 25% of ciliary ganglion cells. After unilateral superior cervical ganglionectomy, galanin-positive nerves almost totally disappear from the iris muscles, demonstrating that they are predominantly of sympathetic origin. Galanin-positive nerves investing the ciliary artery and choroidal blood vessels are not detectably reduced by sympathectomy, indicating that perivascular parasympathetic nerves from the pterygopalatine ganglion also express galanin. Other galanin-containing nerves in the eye can originate from the trigeminal and ciliary ganglia. The prominence of galanin in the ocular autonomic innervation of the cat provides an opportunity to explore the physiological effects of this neuropeptide in the eye.

Statistical power to detect occupationally related respiratory cancer risk in a cohort of female employees in the US man-made vitreous fiber industry

The current update of the US man-made vitreous fiber production worker cohort includes women for the first time. Preliminary comparisons of 3,820 female and 27,767 male workers from 11 participating fibrous glass plants show different hiring patterns during World War II. The gender-specific person-year distributions are similar with respect to duration of employment and time since first employment. The current follow-up of 118,559 person-years for women provides an estimated 80% power to detect a threefold relative risk of respiratory cancer for women who worked more than 14 years in these plants, based on a Poisson regression analysis of the cohort rates. When women comprise a small fraction of the cohort, the statistical power may be inadequate to detect risks of the magnitude typically of interest in studies of men.

Coughing frequency in patients with persistent cough: assessment using a 24 hour ambulatory recorder

Cough is an important symptom of many respiratory disorders. We determined the frequency and diurnal variation of cough in normal subjects and in patients with asthma or with persistent cough of unknown cause. We used a portable, solid-state, multiple-channel recorder to record cough sounds over a 24 h period. The audio-signal was recorded from a unidirectional microphone strapped over the chest wall, and electromyographic (EMG) signals from the lower respiratory muscles were simultaneously registered with surface electrodes. The recorded digital data were examined on an IBM-compatible computer, and the typical signals induced by cough (as assessed by voluntary or experimentally-induced cough) were counted. In 12 normal subjects, only 0-16 coughs were recorded over 24 h. In 21 stable asthmatics with a history of chronic cough ("asthma") the median number was 282 (ranges: 45-1,577), and in 14 patients with the predominant symptom of daily dry coughs ("chronic coughers") the median number was 794 (64-3,639). In both groups of patients, there was a diurnal variation of coughs, such that the least numbers occurred between 2 and 5 a.m. (< 3% of total). In the asthma group, there was no significant correlation between forced expiratory volume in one second (FEV1) (% predicted) or diurnal variation of peak expiratory flow and cough frequency. In the chronic coughers, there was a significant correlation between daytime cough numbers and daytime cough symptoms scores but not for the night-time values. Our data show that cough frequency is not determined by the severity of asthma in relatively stable asthmatics on inhaled steroids, and is reduced during sleep in both asthmatics and chronic cough patients. This portable cough recorder may be useful in the assessment of drug therapy for chronic cough.

Dopamine beta-hydroxylase immunoreactivity in human cerebrospinal fluid: properties, relationship to central noradrenergic neuronal activity and variation in Parkinson's disease and congenital dopamine beta-hydroxylase deficiency

1. Dopamine beta-hydroxylase is stored and released with catecholamines by exocytosis from secretory vesicles in noradrenergic neurons and chromaffin cells. Although dopamine beta-hydroxylase enzymic activity is measurable in cerebrospinal fluid, such activity is unstable, and its relationship to central noradrenergic neuronal activity in humans is not clearly established. To explore the significance of cerebrospinal fluid dopamine beta-hydroxylase, we applied a homologous human dopamine beta-hydroxylase radioimmunoassay to cerebrospinal fluid, in order to characterize the properties and stability of cerebrospinal fluid dopamine beta-hydroxylase, as well as its relationship to central noradrenergic neuronal activity and its variation in disease states such as hypertension, renal failure, Parkinsonism and congenital dopamine beta-hydroxylase deficiency. 2. Authentic, physically stable dopamine beta-hydroxylase immunoreactivity was present in normal human cerebrospinal fluid at a concentration of 31.3 +/- 1.4 ng/ml (range: 18.5-52.5 ng/ml), but at a 283 +/- 27-fold lower concentration than that found in plasma. Cerebrospinal fluid and plasma dopamine beta-hydroxylase concentrations were correlated (r = 0.67, P = 0.001). Some degree of local central nervous system control of cerebrospinal fluid dopamine beta-hydroxylase was suggested by incomplete correlation with plasma dopamine beta-hydroxylase (with an especially marked dissociation in renal disease) as well as the lack of a ventricular/lumbar cerebrospinal dopamine beta-hydroxylase concentration gradient. 3. Cerebrospinal fluid dopamine beta-hydroxylase was not changed by the central alpha 2-agonist clonidine at a dose that diminished cerebrospinal fluid noradrenaline, nor did cerebrospinal fluid dopamine beta-hydroxylase correspond between subjects to cerebrospinal fluid concentrations of noradrenaline or methoxyhydroxyphenylglycol; thus, cerebrospinal fluid dopamine beta-hydroxylase concentration was not closely linked either pharmacologically or biochemically to central noradrenergic neuronal activity. 4. Cerebrospinal fluid dopamine beta-hydroxylase was not changed in essential hypertension. In Parkinson's disease, cerebrospinal fluid dopamine beta-hydroxylase was markedly diminished (16.3 +/- 2.9 versus 31.3 +/- 1.4 ng/ml, P < 0.001) and rose by 58 +/- 21% (P = 0.02) after adrenal-to-caudate chromaffin cell autografts. In congenital dopamine beta-hydroxylase deficiency, lack of detectable dopamine beta-hydroxylase immunoreactivity in cerebrospinal fluid or plasma suggests absent enzyme (rather than a catalytically defective enzyme) as the origin of the disorder. 5. We conclude that cerebrospinal fluid dopamine beta-hydroxylase immunoreactivity, while not closely linked to central noradrenergic neuronal activity, is at least in part derived from the central nervous system, and that its measurement may be useful in both the diagnosis and treatment of neurological disease.

Enhanced expression of nitric oxide synthase by rat retina following pterygopalatine parasympathetic denervation

Removal of the pterygopalatine ganglion enhanced the expression of nitric oxide synthase (NOS) in the ipsilateral rat retina and optic nerve by immunohistochemical and biochemical criteria. The denervation procedure did not alter the apparent histochemical reactivity of retinal cells normally immunoreactive for NOS but did induce expression in retinal ganglion cells and their axons in the retinal nerve fiber layer and optic nerve. After denervation, the induced NOS immunohistochemical reactivity was consistently visualized by day 7, reached a maximum intensity during days 14 to 28, and thereafter gradually attenuated to become barely detectable by microscopy at 10 weeks. Biochemical assays performed two weeks after pterygopalatine denervation confirmed the immunohistochemical observations, especially with regard to the optic nerve. The induced enzyme activity in both retina and optic nerve showed calcium dependency. These results point towards interactions of the ocular parasympathetic innervation and the retina, between which no known neuronal connections exist.

Chromogranin A immunoreactivity in human cerebrospinal fluid: properties, relationship to noradrenergic neuronal activity, and variation in neurologic disease

Although measurement of chromogranin A in the bloodstream is of value in sympathoadrenal investigations, little is systematically known about chromogranin A in cerebrospinal fluid, despite substantial knowledge about its occurrence and distribution in brain. We therefore applied a homologous human chromogranin A radioimmunoassay to cerebrospinal fluid, in order to evaluate the properties and stability of cerebrospinal fluid chomogranin A, as well as its relationship to central noradrenergic neuronal activity, to peripheral (plasma) chromogranin A, and to disease states such as hypertension, renal failure and Parkinsonism. Authentic, physically stable chromogranin A immunoreactivity was found in cerebrospinal fluid (at 37-146 ng/ml; mean, 87.0 +/- 6.0 ng/ml in healthy subjects), and several lines of evidence (including 3.39 +/- 0.27-fold higher chromogranin A in cerebrospinal fluid than in plasma) indicated that it originated from a local central nervous system source, rather than the periphery. Cerebrospinal fluid chromogranin A values were not influenced by administration of effective antihypertensive doses of clonidine or propranolol, and were not related to the cerebrospinal fluid concentrations of norepinephrine, methoxyhydroxyphenylglycol, or dopamine-beta-hydroxylase; thus, cerebrospinal fluid chromogranin A was not closely linked to biochemical or pharmacologic indices of central noradrenergic neuronal activity. Cerebrospinal fluid chromogranin A was not changed (P > 0.1) in essential hypertension (84.2 +/- 14.0 ng/ml) or renal failure (72.2 +/- 13.4 ng/ml), despite a marked (7.1-fold; P < 0.001) increase in plasma chromogranin A in renal failure, and a modest (1.5-fold; P = 0.004) increase in plasma chromogranin A in essential hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Expansion of the retinal pigment epithelium in experimental myopia

Expansion of the retinal pigment epithelium was studied in neonatal chicks after one or two weeks of unilateral form vision deprivation to investigate altered ocular growth mechanisms in this experimental model of myopia. The area of individual retinal pigment epithelial (RPE) cells, measured in tangential sections, was greater in myopic eyes than in contralateral control eyes at both times. The mean RPE cell area in myopic eyes increased to the same extent as the area of the retinal pigment epithelium as a whole. In control eyes between one and two weeks, RPE cell expansion occurred predominantly in the periphery; in myopic eyes, it occurred more generally across the epithelium but was less pronounced in the temporal region. Given the absence of detectable mitotic figures in control and myopic eyes, expansion of the epithelial layer is attributable to passive stretch or growth of existing cells. Whether scleral growth or stretch occurs selectively beneath the areas of more pronounced RPE cell expansion is unknown.

Effect of frusemide on cough responses to chloride-deficient solution in normal and mild asthmatic subjects

We studied the tussive effects of a chloride-deficient solution (1.26% sodium bicarbonate). Nine normal volunteers and 10 mild asthmatic subjects were studied. In two double-blind, placebo-controlled, cross-over studies, we assessed the profile of any inhibitory effects that inhaled frusemide had over these responses. Baseline cough challenge was followed by inhalation of either frusemide (40 mg), or 0.15 M NaCl control. Cough was then induced at 0.5, 2, 4 and 6 h after treatment. Forced expiratory volume in one second (FEV1) was measured before and after each challenge. Changes from the baseline cough response due to drug or control were compared nonparametrically at each time point. There was no difference in the sensitivity of normal and asthmatic subjects to the cough challenge (median cough response 15 and 14.5 on control day, 12 and 15 on frusemide day). Frusemide caused sustained inhibition of the cough response in normal subjects (p < 0.05 at 2 h, p < 0.01 at 4 h), but had only a small, nonsignificant effect in asthmatic subjects at 30 min. Falls in FEV1 of asthmatic subjects due to the chloride-deficient solution were not significant, and did not correlate with number of coughs. We conclude that mild asthmatic subjects are less sensitive than normal subjects to the influence of frusemide against low chloride challenge. This observation is not explained by bronchoconstrictor effects of the cough challenge in asthmatic subjects.

Effect of frusemide on cough responses to chloride-deficient solution in normal and mild asthmatic subjects

We studied the tussive effects of a chloride-deficient solution (1.26% sodium bicarbonate). Nine normal volunteers and 10 mild asthmatic subjects were studied. In two double-blind, placebo-controlled, cross-over studies, we assessed the profile of any inhibitory effects that inhaled frusemide had over these responses. Baseline cough challenge was followed by inhalation of either frusemide (40 mg), or 0.15 M NaCl control. Cough was then induced at 0.5, 2, 4 and 6 h after treatment. Forced expiratory volume in one second (FEV1) was measured before and after each challenge. Changes from the baseline cough response due to drug or control were compared nonparametrically at each time point. There was no difference in the sensitivity of normal and asthmatic subjects to the cough challenge (median cough response 15 and 14.5 on control day, 12 and 15 on frusemide day). Frusemide caused sustained inhibition of the cough response in normal subjects (p < 0.05 at 2 h, p < 0.01 at 4 h), but had only a small, nonsignificant effect in asthmatic subjects at 30 min. Falls in FEV1 of asthmatic subjects due to the chloride-deficient solution were not significant, and did not correlate with number of coughs. We conclude that mild asthmatic subjects are less sensitive than normal subjects to the influence of frusemide against low chloride challenge. This observation is not explained by bronchoconstrictor effects of the cough challenge in asthmatic subjects.

The localization of nitric oxide synthase in the rat eye and related cranial ganglia

Nitric oxide synthase is the biosynthetic enzyme for the free radical neurotransmitter nitric oxide. Using an affinity-purified antiserum, nitric oxide synthase was found to be localized to peripheral ocular nerve fibers, related cranial ganglia, and the retina of the rat. In the eye, nitric oxide synthase-like immunoreactive peripheral nerve fibers were visualized mainly in the choroid and about limbal blood vessels. The anterior uvea was quite sparsely innervated, and the cornea was negative. Many principal neurons in the pterygopalatine ganglion were immunoreactive for nitric oxide synthase while very few cells stained in the superior cervical and trigeminal ganglia. Virtually all nitric oxide synthase-like immunoreactive pterygopalatine cells were also immunostained for vasoactive intestinal polypeptide; nitric oxide synthase also partially co-localized with neuropeptide Y in some of the neurons of this ganglion. Pterygopalatine ganglionectomy significantly reduced the number of peripheral nitric oxide synthase-like immunoreactive nerve fibers in the eye. A variety of immunoreactive retinal cells were seen. Most cells in the inner nuclear layer or ganglion cell layer corresponded morphologically to amacrine cells and displaced amacrine cells. Interplexiform cells and occasional faintly stained cells in the outer portion of the inner nuclear layer also were visualized. Nicotinamide adenine dinucleotide phosphate diaphorase histochemistry generally stained cells of similar distribution but did reveal somewhat more extensive localizations in peripheral ocular tissues, the ciliary ganglion, and the retina, compared with nitric oxide synthase immunohistochemistry. Nitric oxide synthase thus localizes to peripheral ocular nerve fibers, chiefly parasympathetic in nature and derived from the pterygopalatine ganglion, and to several cell types in the retina. Nitric oxide probably acts as a choroidal vasodilator of parasympathetic origin in the eye; the neuropeptide co-localizations in the pterygopalatine ganglion suggest complex neuromodulatory interactions. The retinal localizations imply potential neurotransmitter functions for nitric oxide in this tissue.

Effects of 5-hydroxytryptamine and 5-hydroxytryptophan infusion on the human cough reflex

In some species serotonin (5-HT) has been shown to act as a central modulator of the cough reflex. To investigate whether serotonergic mechanisms influence the control of the human cough reflex, we have induced cough responses before and during infusions of 5-HT; its precursor 5-hydroxytryptophan (5-HTP), which, in contrast to 5-HT, crosses the blood-brain barrier; and saline control. At the start of each study day, eight normal male volunteers were challenged with a single inhalation of a solution lacking chloride ions (0.15 M sodium bicarbonate) and a single breath of capsaicin during a sham infusion. After 3 h they received repeat cough challenges during experimental infusions of 5-HT, 5-HTP, or saline control, which were given randomly and single blind. Heart rate, respiratory rate, and blood pressure were measured before, during, and after each infusion. Both 5-HT and 5-HTP reduced cough responses to the chloride-deficient solution (P = 0.035 and P = 0.017, respectively) with respect to saline control, whereas neither infusion reduced responses to capsaicin. 5-HT caused a transient increase in heart rate that was not observed with a similar dose of 5-HTP or saline (P < 0.01). Respiratory rate and blood pressure were not affected by experimental infusions but rose during cough challenge. We conclude that 5-HT exerts an inhibitory influence over the human cough reflex at peripheral and possibly central sites.

Lung cancer mortality among industrial workers exposed to formaldehyde: a Poisson regression analysis of the National Cancer Institute Study

The Formaldehyde Institute (FI) sponsored additional Poisson regression analysis of lung cancer mortality data from the joint National Cancer Institute (NCI)/FI cohort study of workers exposed to formaldehyde to investigate the previously reported effects of plant and latency period and to assess the impact of short-term workers (under 1 yr employment) on the results. There were 242 lung cancer deaths in this cohort of 20,067 white male workers. With OCMAP software, lung cancer death rates for the white males in this cohort were computed by plant, age, calendar time, and job type for several time-dependent formaldehyde exposures, including formaldehyde exposure in the presence of 12 selected co-exposures: ammonia (AM), antioxidants (AN), asbestos (AS), carbon black (CB), dyes/inks/pigments (DY), hexamethylenetetramine (HX), melamine (ME), particulates (PT), phenol (PH), plasticizers (PL), urea/urea compounds (UR), wood dust (WD), and a composite co-exposure (X5) involving AN, HX, ME, PH, and UR.A 1.6-fold increase in lung cancer risk was found, beginning approximately 16-20 yr after first employment in the study plants with no evidence of a differential effect of latency between hourly and salaried workers or among the various categories of formaldehyde exposure as measured by cumulative average intensity or length of exposure. The statistically significant heterogeneity in lung cancer risk among the 10 plants could not be explained by interplant differences in cumulative or average intensity of exposure to formaldehyde, either without regard to co-exposures or in the presence of any of the 12 co-exposures considered individually. Plant was not a statistically significant predictor of lung cancer risk when cumulative exposure to the composite X5 was included in the model, suggesting that some component of X5, or a correlate, could at least partly account for the overall heterogeneity. No significant associations were found for cumulative, average, or length of exposure to formaldehyde without regard to co-exposure, but positive associations were found for cumulative exposure to formaldehyde in the presence of several co-exposures (AN, HX, ME, PH, and UR). For workers who were never exposed to any of 10 co-exposures associated with an increased lung cancer risk, there was a decreasing pattern of estimated lung cancer risk ratios relative to cumulative formaldehyde exposure. Similar patterns were seen when the analysis was restricted to the long-term workers. Analysis of the internal cohort rates corroborates previous analyses of NCI/FI cohort data in that significant positive associations were found between the risk of lung cancer and cumulative exposure to formaldehyde in the presence of several of the same co-exposures. No such associations were found in the absence of these co-exposures.

The low-chloride cough response is not inhibited by a single, high dose of aspirin

The effect of a single, high dose of aspirin has been assessed against low chloride cough challenge. The drug does not affect the cough response, suggesting that airway prostaglandin generation is not responsible for the tussive activity of low chloride solution.

Baroreflex sensitivity and heredity in essential hypertension

BACKGROUND

Abnormalities in baroreflex control of heart rate may be important in the pathogenesis of essential hypertension.

METHODS AND RESULTS

To investigate the influence of heredity on baroreflex function, we measured baroreflex sensitivity in 40 untreated patients with essential hypertension grouped by the presence (FH+) or absence (FH-) of a family history of hypertension and in 24 normotensive counterparts. Baroreflex sensitivity was assessed by both high-pressure (phenylephrine bolus) and low-pressure (amyl nitrite inhalation) stimuli. Subject groups were matched for age, blood pressure, body weight, and race. Baroreflex sensitivity (in milliseconds per millimeter of mercury) assessed by amyl nitrite inhalation was 24.3 +/- 2.8 in FH- normotensives, 12.3 +/- 1.7 in FH+ normotensives, 15.4 +/- 3.3 in FH- hypertensives, and 8.1 +/- 1.2 in FH+ hypertensives. Baroreflex sensitivity assessed by phenylephrine bolus was 28.8 +/- 5.6 in FH- normotensives, 19.3 +/- 2.8 in FH+ normotensives, 19.1 +/- 2.0 in FH- hypertensives, and 13.6 +/- 1.3 in FH+ hypertensives. Two-factor analysis of variance showed significant effects on baroreflex sensitivity for blood pressure status (normotensive versus hypertensive) and for family history of hypertension. After control line (controlling) for the effects of several variables, including age, mean arterial pressure, body weight, and race through multiple linear regression analysis, the effect of family history of hypertension on baroreflex sensitivity was still highly significant. Indeed, of all variables investigated, family history of hypertension was the strongest unique baroreflex sensitivity predictor.

CONCLUSIONS

These data suggest that the impairment in baroreflex sensitivity in hypertension is in part genetically determined and may be an important hereditary component in the pathogenesis of essential hypertension.