Seven-day holter monitoring detects more significant arrhythmias than 24-hour and 3-day monitoring

Funding Acknowledgements

Type of funding sources: None.

Background/Introduction

24-hour Holter monitors have been used widely to assess patients with suspected and known arrhythmias. Recent studies have shown increased yield of arrhythmia detection with longer durations of Holter monitoring.

Purpose

The aim of the study was to evaluate the incremental yield in significant arrhythmias detected using a 7-day continuous Holter monitor, as compared to what can be achieved within a 24-hour and 48 to 72 hours study.

Methods

A retrospective study of patients from 72 sites in two geographical locations, A and B, who completed a continuous 7-days patch monitor study was performed. 801 of these studies detected significant arrhythmias; pauses 3 seconds or more (PA), ventricular tachycardia of 6 beats or more (VT), and paroxysmal atrial fibrillation (PAF). The day of the first occurrence of a significant arrhythmia was noted and tallied to determine the incremental yield of a multiday Holter monitoring.

Results

Of 801 total cases detected with significant arrhythmia, only 278 (35%) were detected in the first 24hours, while 523 (65%) cases were detected after Day 1. 331 (41%) had first significant arrhythmia detected after the 3rd day of monitoring, with 68 (44%) being PA, 125 (40%) PAF, and 138 (41%) VT. Notably, in Group A, 31 (72%) of total VT detected and 35 (72%) of total PAF detected were first picked up after Day 1, 21 (49%) of total VT were first detected only after the 3rd day of monitoring.

Conclusions

1-day (24-hour) monitoring period fails to detect a significant number of potentially serious cardiac arrhythmias. Extended continuous Holter monitoring increases the yield of detection, with a substantial fraction (40-49%) detected after the 3rd day of monitoring. No difference in results obtained between two geographical locations demonstrates strong evidence that findings are consistent across different sites. Review of current practice and guidelines is necessary to further expand usage of multiday Holter monitoring, thus increasing benefits to patients.

Equatorial wrinkles in the human lens capsule

Equatorial wrinkles, or crenations, have been previously observed around the equator in coronal images of the human ocular lens. However, wrinkles are typically not apparent when the lens is viewed from saggital directions. In the current paper, the existence and geometry of these wrinkles is shown to be consistent with a mechanical model of the isolated lens, in which the capsule is held in a state of residual tension by a spatially uniform internal pressure. The occurrence of equatorial wrinkles is therefore seen to be a mechanical consequence of the spheroidal shape of the lens capsule and an excess intralenticular pressure. New observations are made, on post mortem lenses, on the geometric arrangement of these equatorial wrinkles. These observations indicate a well-defined pattern in which wrinkles exists along meridional lines in the equatorial regions of the lens. A preliminary 'puncture test' is used to demonstrate that the residual stresses within the capsule in the equatorial region of the lens are broadly consistent with the proposed mechanical model of the lens capsule. It is suggested that the presence of equatorial wrinkles may have an influence on the mechanical performance of the capsule during the accommodation process.

The ageing lens and cataract: a model of normal and pathological ageing

Cataract is a visible opacity in the lens substance, which, when located on the visual axis, leads to visual loss. Age-related cataract is a cause of blindness on a global scale involving genetic and environmental influences. With ageing, lens proteins undergo non-enzymatic, post-translational modification and the accumulation of fluorescent chromophores, increasing susceptibility to oxidation and cross-linking and increased light-scatter. Because the human lens grows throughout life, the lens core is exposed for a longer period to such influences and the risk of oxidative damage increases in the fourth decade when a barrier to the transport of glutathione forms around the lens nucleus. Consequently, as the lens ages, its transparency falls and the nucleus becomes more rigid, resisting the change in shape necessary for accommodation. This is the basis of presbyopia. In some individuals, the steady accumulation of chromophores and complex, insoluble crystallin aggregates in the lens nucleus leads to the formation of a brown nuclear cataract. The process is homogeneous and the affected lens fibres retain their gross morphology. Cortical opacities are due to changes in membrane permeability and enzyme function and shear-stress damage to lens fibres with continued accommodative effort. Unlike nuclear cataract, progression is intermittent, stepwise and non-uniform.

Successful Treatment of Sexual Disinhibition in Dementia with Carbamazepine

Sexual disinhibition is a disturbing behavioral symptom in dementia. At present, there are no treatment guidelines available. Here we present the successful use of carbamazepine in a 78-year old AD patient with hypersexual behavior. The efficacy of carbamazepine in this case is in parallels to its effects on aggression and agitation in dementia and supports the important role of anticonvulsants in the management of behavioral disturbances in demented patients.

Work-related trauma: the experiences of perioperative nurses

Traumatic experiences in the workplace are an integral part of the role of the perioperative nurse. The atypical nature and characteristics of these experiences is such that perioperative nurses may suddenly encounter reactions and feelings that are very different and more intense than anything they will have encountered previously. Furthermore, these events may increase the risk of them experiencing subsequent trauma stress reactions and place them at risk of profound distress and significantly impaired functioning. A survey of 233 nurses working in rural and metropolitan operating theatres assessed the range and types of traumatic work experiences. Results showed that exposure to traumatic events was reported by 161 (69%) of all respondents and a wide range of traumatic experiences were reported to have affected their well-being. The findings have implications for the formulation of trauma management strategies, both at individual and organisational levels and suggest new directions for education and research in promoting a recovery environment in which perioperative nurses can work.

EFFECT OF ACUTE BRAIN DEATH ON RELEASE OF ATRIUM AND B-TYPE NATRIURETIC PEPTIDES IN AN ANIMAL MODEL

INTRODUCTION

Atrium and B-type natriuretic peptides (ANP and BNP) and big endothelin (ET)-1 are markers for severity of heart failure and may be used in the quality assessment of donor hearts. Elevated cardiac troponins predict early graft failure after heart transplantation. This study evaluated the effects of acute brain death (BD) on the release of ANP, BNP, big ET-1, and cardiac troponins in an animal model.

MATERIALS AND METHODS

Pigs were randomized into a BD group (n=5) and a control group (n=5). In the first group, acute BD was induced, and anesthesia was stopped. In the control animals, a sham operation was performed, and anesthesia was continued. Parameters were measured at baseline and for 13 hours postoperatively.

RESULTS

After acute BD, there were significant hemodynamic changes. In the control group, the BNP level was higher than in the BD group and decreased over time (P =0.016). There was no significant change in BNP release in the BD group up to 13 hours (P =0.1). ANP release remained stable over time in the control group (P =0.35) but decreased in the BD group (P =0.043). The big ET-1 levels were not different between groups. Cardiac troponin I was elevated in the BD group 5 hours after BD (P< 0.05) but remained under 1.5 mg/L throughout the study.

CONCLUSION

Acute BD did not lead to an increase of BNP and ANP levels. Moreover, intact brain function seems to augment the release of natriuretic peptides from the myocardium. Further clinical evaluation of prognostic values of natriuretic peptides for the assessment of donor hearts is necessary. Cardiac troponins are a useful additional tool in the evaluation of donor hearts.

Uvulopalatopharyngoplasty for sleep apnea in mentally retarded obese 14-year-old: an anaesthetic challenge

Anaesthetic management of patients with obstructive sleep apnea for upper airway surgery has always been a challenging task. We report our anaesthetic approach for a young, mentally retarded obese patient with documented obstructive sleep apnea undergoing uvulopalatopharyngoplasty. The therapeutic intervention before, during and after operation is discussed.

Epidural buprenorphine in management of pain in multiple rib fractures

BACKGROUND

Pain from multiple rib fractures may affect pulmonary function, morbidity, and length of stay in the intensive care units. This study describes some clinical characteristics of epidural buprenorphine, a lipophilic and partial opiate agonist with a higher micro receptor affinity than morphine, in combating the pain in multiple rib fractures.

METHODS

The study was conducted prospectively over a 15-month period. A total of 27 patients admitted to the hospital with multiple rib fractures were studied. Buprenorphine at a concentration of 0.3 mg in 5-10 ml normal saline was administered epidurally, twice daily the first 24 h, thereafter once daily. Ventilatory function tests (including vital capacity, tidal volume, respiratory rate, and minute volume) and assessment of pain intensity using a simple, categorical, verbal rating scale were obtained before and after institution of analgesia. Any nausea, vomiting, hypotension, urinary retention, respiratory depression or pruritus were recorded.

RESULTS

We found a significant improvement in ventilatory function tests during the 1st, 2nd, and 3rd day after epidural analgesia when compared with the preanalgesia levels (P < 0.001). Changes in the verbal rating scale demonstrated that epidural buprenorphine was associated with marked improvement in pain at rest and pain during coughing and deep breathing. None of our patients developed hypotension (<10% of the baseline), urinary retention or respiratory depression. Nausea, vomiting, and mild pruritus were the only reported complications.

CONCLUSIONS

Epidurally introduced narcotic, like buprenorphine in saline, has been found to be effective in our study to achieve adequate analgesia in treatment of patients with multiple rib fractures. In addition, this methodology of pain relief eliminates the costly delivery system and early discharge, and allows walking epidurals and follow-up on outpatient basis.

Loss of bone mass and vitamin D deficiency after hematopoietic stem cell transplantation: standard prophylactic measures fail to prevent osteoporosis

Bone mineral density (BMD) and biochemical markers of bone metabolism were analyzed in 67 adults with ALL (n = 27), AML (n = 14), MDS (n = 6) and CML (n = 20) before and after allogeneic stem cell transplantation (SCT). Median age was 36 years (17-56). Twenty-six out of 53 patients (49%) had osteopenia and osteoporosis before SCT, 21/26 had acute leukemias and 5/26 had chronic myeloid leukemia (CML). T-score before SCTwas -1.23 in patients with acute leukemias and 0.62 in CML patients (P = 0.001). After SCT, a significant loss of BMD was observed in all patients. After 6 months, 24 of 36 evaluable patients (67%) had pathologic BMD, 11 of them (30%) had developed osteoporosis. After 12 months, 20 of 32 evaluable patients (62%) had BMD values below normal and nine of them (28%) had osteoporosis. Increased pyridinium excretion was observed in 12/20 patients (60%) with acute leukemias, but only in 3/13 (23%) with CML (P = 0.014). A prolonged vitamin D deficiency for more than 6 months developed early after SCT in all patients. Patients with acute leukemias frequently have osteopenia and osteoporosis before SCT. After SCT, a further loss of BMD occurs independent from the underlying disease. Standard prophylactic measures are not sufficient to prevent loss of bone mass. Studies on prophylactic interventions are needed to prevent severe osteoporosis in long-term survivors of SCT.

Continuous thoracic epidural anesthesia with 0.2% ropivacaine versus general anesthesia for perioperative management of modified radical mastectomy

We evaluated in this prospective study the effectiveness of continuous thoracic epidural anesthesia (TEA) and postoperative analgesia with ropivacaine and compared it with general anesthesia (GA) and opioids for pain relief, side effects, postanesthesia recovery, and hospital discharge after modified radical mastectomy. Sixty ASA physical status II and III patients undergoing mastectomy were randomly assigned to two study groups of 30 patients each. In the TEA group, an epidural catheter was inserted at T6-7, and 5--10 mL of 0.2% ropivacaine was injected to maintain anesthesia and to continuously administer adequate analgesia for 48 h. GA was induced with IV 1--2 mg of midazolam or 50--100 microg/mL of fentanyl followed by 50--150 mg of propofol and was maintained with sevoflurane and 50% N(2)O in oxygen. The Aldrete score system was used to evaluate postanesthesia recovery, a verbal rating scale was used for assessment of pain intensity, and a postanesthesia discharge scoring system was used for discharge home. The demographic data and side effects (except for nausea and vomiting) (GA 43%, TEA 10%, P = 0.0074) and discharge home were similar in both groups. However, the number of patients ready for discharge from the recovery room during the first postanesthesia hour (Aldrete score of 10) was significantly larger after TEA (80%) than after GA (33%) (P = 0.0006). GA patients experienced significantly more (P < 0.001) substantial pain than TEA patients on Day 0 (70%), Day 1 (53%), and Day 2 (27%) after the surgery. Patient satisfaction was greater with TEA (70%) than with GA (30%) (P < 0.001). We conclude that TEA with ropivacaine provides better postoperative pain relief and less nausea and vomiting, facilitates postanesthesia recovery, and gives greater patient satisfaction than GA.

Lens growth and protein density in the rat lens after in vivo exposure to ultraviolet radiation

PURPOSE

To investigate lens growth after different doses of ultraviolet radiation (UVR) and to investigate the long-term effect of a near-threshold UVR dose on the refractive index distribution in the lens.

METHODS

Sprague-Dawley rats received UVR (lambda(MAX) = 300 nm) unilaterally during a 15-minute period. The exposure dose ranged from 0.1 to 20 kJ/m(2), and the rats were kept for up to 32 weeks after exposure. Intact lenses were photographed and lens wet and dry masses were measured. The protein density was estimated by quantitative microradiography. Freeze-dried lens sections were used for contact x-ray photographs. From the transmission of the microradiographs, protein density and refractive index profiles were calculated along the lens radius with a resolution of 2.5 microm.

RESULTS

Lens dry mass in exposed eyes was lower than in nonexposed eyes at one week after exposure. Lens water content was decreased after low UVR doses but increased after high doses. The difference between exposed and nonexposed lenses in dry mass and water content increased with time after exposure. No significant difference was found for the mean protein density in exposed and nonexposed lenses. The protein density increased linearly in the lens cortex, from a minimum in the superficial cortex of 0.26 g/cm(3) to a maximum in the deep cortex of 0.81 g/cm(3). This corresponded to a refractive index of 1.38 and 1.48, respectively.

CONCLUSIONS

Lenses exposed to UVR grew more slowly than their nonexposed contralaterals. This growth inhibition was dose dependent. Near-threshold doses led to decreased water content in the lens whereas high doses led to swelling. Six months after near-threshold UVR exposure, no global change of the refractive index was found. However, local variations of the refractive index caused a subtle cortical light scattering.

Recovery From Work-Related Trauma by Perioperative Nurses

The complexities of the recovery process following a traumatic event suggest a need to provide support resources that sustain or promote positive perceptions of the events. The availability and effectiveness of social support is a function of both its content and its capability of responding appropriately to the influence of the recovery dynamics in a contingent manner. Further, the quality of recovery from work-related trauma is suggested to be a function of the interactive processes of the individuals, the organisational environment they work in, and the social support provided. Using methodological triangulaton, 213 nurses working in rural and metropolitan operating suites were surveyed to assess the types, amount and effectiveness of social and personal resources that were used following exposure to traumatic work experiences. The findings demonstrate the significance of personal and social support resources in assisting perioperative nurses to recover from traumatic experiences. A personal sense of coherence and emotional support received through disclosure to work colleagues and supervisors were the most salutary aspects of support following trauma. The results suggest that opportunities should be made available through peer support programs, educational programs and professional meetings to better prepare nurses for traumatic situations and their aftermath. Furthermore, the work organisation needs to be educated in the need for and process of creating sanctuary and providing a holistic approach to management. This will then allow individuals, such as perioperative nurses, to continue to function at an acceptable level during the mitigation of the traumatic incident.

The impact of work-related trauma on the well-being of Perioperative Nurses

Perioperative nurses are confronted daily with the reality of trauma, of experiencing abuse and conflict in the workplace, dealing with practice issues such as gruesome motor vehicle accidents, as well as the heartbreaking tragedy of death (Michael 1999, Michael & Jenkins 2000). This study explored the reported impact of traumatic events upon the well-being of perioperative nurses, using both qualitative and quantitative methods of inquiry. Of the 233 respondents in this study, 161 (69%) reported being exposed to traumatic events. The types of described reactions following trauma were predominantly negative and included negative feelings, negative team member relationship issues, negative behaviour from others, physical concerns and negative working conditions. Intrusion and avoidance behaviour was reported to a significant degree. Performance distress, somatic distress, general feelings of distress and self-related health were significantly poorer in perioperative nurses who had experienced trauma, than their colleagues without such experiences. Conversely, some respondents were able to construe positive outcomes from trauma and grow from the experience. Positive outcomes included gains from the experience, team building, positive feelings and action taken. The current study contributes to understanding of the role of environmental factors, associated work-related trauma and recovery following such events. The outcomes have implications for effective trauma stress management interventions and continuing education of nurses.

Epidural blood patch after thoracotomy for treatment of headache caused by surgical tear of dura

IMPLICATIONS

During a right lobectomy operation, a patient with carcinoma of the lung developed postoperative headache caused by a leak of cerebrospinal fluid from an area of dura injured during the procedure. Conservative treatment was unsuccessful. Injection of 10 mL of the patient's own blood into the epidural space relieved the headache.

Influence of exposure time for UV radiation-induced cataract

PURPOSE

It is believed that for a certain ultraviolet radiation (UVR) exposure, the biologic effect depends on the product of irradiance and exposure time (the reciprocity Bunsen-Roscoe law). The purpose of this study was to investigate the validity of the reciprocity law for UVR-induced cataract.

METHODS

Two experiments were conducted. In the first one, 100 Sprague-Dawley rats were exposed to UVR divided into five groups according to exposure time: 7.5, 15, 30, 60, and 120 minutes. In the second experiment, 80 Sprague-Dawley rats were exposed to UVR divided into four groups according to exposure time: 5, 7.5, 11, and 15 minutes. All the animals were unilaterally exposed to the same dose of UVR (8 kJ/m(2)) in the 300-nm wavelength region. One week after exposure both lenses were removed to measure the intensity of forward light scattering and for microphotography. Groups were compared by evaluating the difference between exposed and nonexposed eyes.

RESULTS

The group exposed to UVR for 5 minutes had the lowest intensity of forward light scattering. The highest intensity of forward light scattering was found in the group that was exposed for 15 minutes. With longer exposure intervals, the intensity of forward light scattering decreased as the exposure time increased. No difference in intensity of forward light scattering was found between the groups exposed for 60 and 120 minutes. CONCLUSIONS; Exposure time strongly influenced cataract formation after low-dose UVR. In this model of UVR-induced cataract, the photochemical reciprocity law was modulated by a biologic response.

Change in muscle mass and muscle strength after a hip fracture: relationship to mobility recovery

BACKGROUND

Hip fracture in elderly persons has a serious impact on long-term physical function. This study determines the change in muscle strength and muscle mass after a hip fracture, and the associations between these changes and mobility recovery.

METHODS

Ninety community-dwelling women aged 65 years and older who had recently experienced a fracture of the proximal femur were included in the study. At 2 to 10 days after hospital admission, the women's grip strength, ankle dorsiflexion strength, and regional muscle mass (by dual-energy x-ray absorptiometry) were measured, and the prefracture level of independence for five mobility function items was assessed. All measurements were repeated at 12 months.

RESULTS

At follow-up, only 17.8% of the women had returned to their prefracture level of mobility function for all five items. Mobility function recovery was not related to change in skeletal muscle mass of the nonfractured leg or the arms. However, women who lost grip strength (mean loss of -28.7%, SD = 16.9%), or who lost ankle strength of the nonfractured leg (mean loss of -21.5%, SD = 14.7%), had a worse mobility recovery compared with those who gained strength (p = .04 and p = .09, respectively). In addition, chronic disease (p = .03), days hospitalized (p = .04), and self-reported hip pain (p = .07) were independent predictors of decline in mobility function.

CONCLUSIONS

The results suggest that loss of muscle strength, but not loss of muscle mass, is an independent predictor of poorer mobility recovery 12 months after a hip fracture. When confirmed by other studies, these findings may have implications for rehabilitation strategies after a hip fracture.

An action spectrum for UV-B radiation and the rat lens

PURPOSE

To determine an action spectrum for UV-B radiation and the rat lens and to show the effect of the atmosphere and the cornea on the action spectrum.

METHODS

One eye of young female rats was exposed to 5-nm bandwidths of UV-B radiation (290, 295, 300, 305, 310, and 315 nm). Light scattering of exposed and nonexposed lenses was measured 1 week after irradiation. A quadratic polynomial was fit to the dose-response curve for each wave band. The dose at each wave band that produced a level of light scattering greater than 95% of the nonexposed lenses was defined as the maximum acceptable dose (MAD). Transmittance of the rat cornea was measured with a fiberoptic spectrophotometer. The times to be exposed to the MAD in Stockholm (59.3 degrees N) and La Palma (28 degrees N) were compared.

RESULTS

Significant light scattering was detected after UV-B at 295, 300, 305, 310, and 315 nm. The lens was most sensitive to UV-B at 300 nm. Correcting for corneal transmittance showed that the rat lens is at least as sensitive to UV radiation at 295 nm as at 300 nm. The times to be exposed to the MAD at each wave band were greater in Stockholm than in La Palma, and in both locations the theoretical time to be exposed to the MAD was least at 305 nm.

CONCLUSIONS

After correcting for corneal transmittance, the biological sensitivity of the rat lens to UV-B is at least as great at 295 nm as at 300 nm. After correcting for transmittance by the atmosphere, UV-B at 305 nm is the most likely wave band to injure the rat lens in both Stockholm and La Palma.

Development and repair of cataract induced by ultraviolet radiation

BACKGROUND

Several epidemiological investigations show a correlation between cataract development and the dose of ultraviolet radiation (UVR) received. It is experimentally well established that exposure of animal eyes to UVR induces cataract. Most cataracts develop as a gradual increase in lens opacity. Despite this, current estimations of toxicity for cataract are based on the concept that cataract is a binary event. Moreover, current exposure limits for UVR are based on subjective inspections with slit lamp microscopy.

PURPOSE

The first purpose of the present study was to determine a statistically defined maximum acceptable dose for ultraviolet radiation-induced cataract based on quantitative data of forward light scattering in lenses. The second purpose was to find possible explanations for light scattering by investigating the morphology and the refractive index distribution in the lens. The third purpose was to describe the development of cataract after UVR on the cellular level.

METHODS

Six-week-old, female Sprague-Dawley rats received UVR unilaterally in vivo. The radiation from a high pressure mercury lamp was collimated, passed through a water filter and an interference filter or a monochromator (lambdaMAX = 300 nm), and projected onto the cornea. The exposure time was 15 min. The exposure dose ranged between 0.1 and 20 kJ/m2 and the animals were kept between 6 hours and 32 weeks after exposure. The extracted lenses were photographed and forward light scattering was measured. Other methods included light microscopy, fluorescence microscopy, transmission and scanning electron microscopy, freeze-fracture and microradiography.

RESULTS AND CONCLUSIONS

From a long-term experiment, it was concluded that UVR-exposed lenses scatter light more than their contralaterals and that a higher dose induces more light scattering. After exposure to 5 kJ/m2, the mean forward light scattering remains unchanged between 1 and 32 weeks. Earlier observations, taken together with the current findings, indicate that the optimal time to detect low dose UVR-induced cataract is one week after exposure in rats. The intensity of forward light scattering increases exponentially with increased UVR dose between 0.1 and 14 kJ/m2. Based on this continuous dose-response, a method to determine a maximum acceptable dose to avoid UVR-induced cataract was developed. The statistically defined lower limit of pathologic light scattering is projected on the dose-response function. The dose corresponding to that point can be estimated and was suggested to be called the Maximum Acceptable Dose (MAD). Two low dose UVR exposures with 0 or 6 h intervals between the exposures produce the same degree of lens opacification. When the second exposure follows 24 or 48 h after the termination of the first, lenticular damage increases. Repair processes between 24 and 48 h after exposure appear to be sensitive to UVR, and an additional exposure during this time may aggravate cataract development. Lenses exposed to UVR grow more slowly than their non-exposed contralaterals. This decrease in lens growth was more pronounced with increasing dose. Low doses led to decreased water content in the lens whereas high doses led to swelling. At 6 months after low dose UVR exposure, no global change of the refractive index was found. However, local variations of the refractive index induce a subtle cortical light scattering. In vivo low dose UVR induces programmed cell death which peaks 24 h post-exposure and involves the entire lens epithelium. Dead cells are removed from the epithelium by phagocytosis. This leads to disintegration of the lens epithelium, associated with flake-like opacities at the lens surface. After one week, the epithelium and the equatorial parts of superficial lens fibers contain extracellular spaces. The extracellular spaces together with locally disarranged fibers produce a corrugated opaque lens surface and equatorial opacities. Within several weeks after ex

In vivo cataract after repeated exposure to ultraviolet radiation

The purpose of this study was to investigate the effects of repeated close-to-threshold ultraviolet radiation (UVR) doses in the rat lens. Sprague Dawley rats received two UVR exposures (lambda(max) = 300 nm, lambda0.5 = 10 nm) separated by different time intervals. The animals were unilaterally irradiated with 4 kJ m(2-1) UVR in each exposure. The intervals between both exposures were: 6 hr, 1 day, 3 days, 9 days and 30 days. At 1 week after the last exposure both lenses were removed, microphotographs were taken and intensity of forward light scattering was measured. Evaluating the difference between exposed and non-exposed eyes, the forward light scattering in the 6 hr and 1 day interval group was not significantly different. The most intense forward light scattering was found in the group that was allowed 3 days interval between exposures. Thereafter, the intensity of scattering decreased as the time interval between exposures increased. The lowest intensity of forward light scattering was detected in the 30 days interval group. Three days after a UVR exposure, the lens showed the highest sensitivity for a second UVR exposure. One month after the first exposure lenses undergo physiological repair and interactions between exposures seem to decrease.

Repair in the rat lens after threshold ultraviolet radiation injury

PURPOSE

To investigate the development and recovery of lens damage after in vivo close-to-threshold exposure to ultraviolet B radiation.

METHODS

One eye of young, female Sprague-Dawley rats was exposed to 5 kJ/m2 narrowband ultraviolet radiation (UVR) (lambda(max) = 302 nm) for 15 minutes. Groups of rats were killed 1, 7, and 56 days after exposure. The structure of the exposed and nonexposed lenses was examined with light microscopy, scanning electron microscopy, transmission electron microscopy, freeze-fracture, fluorescent membrane staining, and Fourier transform analysis.

RESULTS

One day after UVR exposure the lens surface had flakelike opacities. Seven days after exposure, the lens surface appeared opaque and corrugated, and the equatorial cortex had small opacities. At 56 days postexposure, the surface and equator appeared clear, but the cortex had a subtle shell-shaped opacity. At 1 day postexposure, apoptotic cell death occurred in the lens epithelium, but the cortical fibers were normal. At 7 days postexposure, the epithelium and the fibers between the 10th and 40th growth shell below the capsule contained extracellular spaces of different sizes. After 56 days, the epithelial layer appeared normal, and the extracellular spaces had disappeared; but abnormal fibers were found between the 60th and 100th growth shell below the capsule. Fibers above and below the damaged growth shells appeared fully normal.

CONCLUSIONS

A close-to-threshold dose of UVR causes cataract, which is largely reversible. The UVR exposure leads to apoptosis in the lens epithelium, and after a latency period of several days, lens fibers are abnormal. Extracellular spaces develop in the epithelium and fibers. Within several weeks after exposure, the epithelium fully recovers and new fibers develop normally. The originally affected fibers are repaired. However, this repair is incomplete, leaving a small zone of enhanced light scattering in the equatorial cortex.

Loss of bone density and lean body mass after hip fracture

Few studies of bone loss have assessed the amount of loss directly after a hip fracture. The present prospective study was conducted to determine changes in bone mineral density (BMD) and muscle mass shortly after fracture and through 1 year to assess short-term loss and related factors. The setting was two acute care teaching hospitals in Baltimore, Maryland, and subjects were 205 community-dwelling women with a new fracture of the proximal femur between 1992 and 1995. Bone density of the nonfractured hip and whole-body and body composition were measured by dual-energy X-ray absorptiometry at 3 and 10 days and 2, 6 and 12 months after admission. Mean BMD of the femoral neck was 0.546 +/- 0.007 g/cm(2) at baseline. Average loss of femoral neck BMD from baseline was 2.1% at 2 months, 2.5% at 6 months and 4.6% at 12 months. The average loss of BMD in the intertrochanteric region was 2.1% at 12 months. Total lean body mass decreased by 6% while fat mass increased by 3. 6% by 1 year after the fracture. These findings indicate that significant loss in BMD and lean body mass occur shortly after hip fracture while body fat increases. Continued loss was evident throughout the 1 year of follow-up. This loss of both bone density and muscle mass may lead to new fractures.

Lens opacities after repeated exposure to ultraviolet radiation

PURPOSE

To investigate the effect of the interval between two, near-threshold exposures to ultraviolet radiation (UVR) on cataract development.

METHODS

One eye of Sprague-Dawley rats was exposed twice to 4 kJ/m2 narrow band UVR (lambdaMAX=300 nm) for 15 min each. The interval between exposures was 0, 6, 24 or 48 h. One week after the first exposure both lenses were removed for photography and measurement of the intensity of forward light scattering to quantify lens opacities.

RESULTS

All exposed lenses developed cataract. Forward light scattering was the same after double exposure with no interval or a 6 h interval. Forward light scattering after a 24 or 48 h interval was nearly twofold greater than that following no interval or a 6 h interval. The exposed lenses in all groups had mild anterior surface opacities and intense equatorial opacities as judged with a stereomicroscope.

CONCLUSION

Two, near-threshold UVR exposures at 0 or a 6 h interval produce the same degree of lens opacification. When the second exposure follows 24 or 48 h after the first, lenticular damage increases. Repair processes between 24 and 48 h after exposure appear to be sensitive to UVR, and an additional exposure during this time may aggravate cataract development.

Effect of follicular cells on calcitonin gene expression in thyroid parafollicular cells in cell culture

Expression of calcitonin (CT) gene in thyroid parafollicular cells involves alternate formation of CT mRNA or CGRP mRNA. High amounts of CT mRNA are formed only in thyroid gland and formation of CGRP mRNA dominates in the remaining organs. Apart from paracrine and endocrine factors, mRNA formation on the CT gene seems to be affected also by direct contacts with other cells present in the thyroid gland, in which parafollicular cells are located next to follicular cells. The present study aimed at examining whether thyroid follicular cells affect formation of mRNAs for CT and CGRP in parafollicular cells. The studies were performed in cell cultures. A parafollicular cell line (TT cells) and a follicular cell line (F6BTY cells) served as the experimental model. For comparison, co-cultures with fibroblasts, 3T3 cells, and malignant melanoma, MM cells, were also examined. CT gene expression was examined at the level of mRNAs (in situ hybridization and morphometric studies) and at the level of hormones (immunocytochemistry, morphometric studies and radioimmunological estimation of hormone levels in the medium). The immunocytochemical and hybridocytochemical studies, in line with morphometry studies, demonstrated that F6BTY and 3T3 cells were capable of affecting mRNA production for CT and CGRP and that they changed the ratio of CGRP/CT secretion by TT cells, as a sequel of contact between the two cell types and due to mediation of secreted substances. On the other hand, the malignant melanoma MM cells showed no effect on the secretion ratio. Our study seems to indicate that control of mRNA formation from CT gene may involve not only humoral factors but also direct contacts with other cells, which may explain differences in expression of the gene between cells localized in different organs.

Apoptosis in the rat lens after in vivo threshold dose ultraviolet irradiation

PURPOSE

To investigate DNA damage in the rat lens after in vivo close-to-threshold exposure to ultraviolet radiation (UVR).

METHODS

Sprague-Dawley rats received 5 kJ/m2 UVR (lambdaMAX = 300 nm, lambda0.5 = 10 nm) unilaterally for 15 minutes. Animals were killed at 1, 6, and 24 hours and at 1 week after exposure. DNA-strand breaks were investigated in sagittal paraffin sections using the TdT-dUTP terminal nick-end labeling (TUNEL) technique and propidium iodide for counterstaining. Other lenses were prepared for transmission electron microscopy (TEM).

RESULTS

TUNEL-positive nuclei were found at only 24 hours after UVR exposure. About one tenth of the epithelial cell nuclei were TUNEL positive, and affected cells were scattered over the entire epithelium. No TUNEL-positive cells were found at 1 or 6 hours or at 1 week after UVR exposure or in the nonexposed lenses. TEM verified the occurrence of programmed cell death and showed the breakdown of the apoptotic cells by adjacent cells. No signs of necrosis were found.

CONCLUSIONS

Threshold-dose UVR induces programmed cell death that peaks 24 hours after exposure and involves the entire epithelium. Dead cells are removed from the epithelium by phagocytosis.

Outpatient costing and classification: are we any closer toa national standard for ambulatory classification systems?

The Outpatient Costing and Classification Study was commissioned by the Department of Health and Family Services to evaluate the suitability of the Developmental Ambulatory Classification System (DACS). Data on the full range of ambulatory services (outpatient clinics, emergency departments and allied health services) were collected prospectively from a stratified sample of 28 public hospitals. Patient encounters captured in the study represent 1% of the total ambulatory encounters in Australia in one year. Costing per encounter included time spent with the patient, cost of procedures, indirect costs (salaries and consumables), overhead costs and diagnostic costs. The most significant variable explaining cost variation was hospital type, followed by outpatient clinic type. Visit type and presence or absence of a procedure--major splits for the proposed DACS--did not produce splits that were consistent across all hospital strata. The study found that DACS is not an appropriate classification for hospital ambulatory services. A clinic-based structure for outpatients and allied health departments is recommended for classifying and funding ambulatory services in Australia.

Transcription Factor E2F Controls the Reversible γδ T Cell Growth Arrest Mediated Through WC1

IL-2-stimulated expansion of T cells requires continued and sequential passage of the dividing cells through a major cell cycle check point in the G1 phase. We have previously shown that a γδ T cell-specific surface receptor, WC1, induces G0/G1 growth arrest, reversible with Con A, in proliferating IL-2-dependent γδ T cells. We now show that this reversible WC1-induced cell cycle arrest is correlated with induction of the cyclin kinase inhibitor p27kip1 and an associated down-regulation in cyclins A, D2, and D3 expression, along with dephosphorylation of pocket proteins p107, p130, and pRb. Together with diminished pocket protein phosphorylation, p107 expression levels are significantly down-regulated in response to WC1 stimulation. This coordinated sequence of signaling events is focused on E2F regulation so that, downstream of the pocket proteins, WC1 stimulation results in a diminished DNA binding activity for free E2F as a consequence of reduced E2F1 expression, whereas E2F4 expression is unaffected. Consistent with this interpretation, overexpression of E2F1 overcomes the growth-arresting effects induced by WC1 stimulation. Finally, in accordance with our previous observations at both the cellular and molecular level, subsequent mitogen stimulation can reverse all the above changes induced by WC1. These results, focused on E2F regulation, therefore provide a first insight into the effects of both positive (mitogen) and negative (anti-WC1) stimuli on cell cycle control in IL-2-dependent γδ T cells.

Dose-response function for lens forward light scattering after in vivo exposure to ultraviolet radiation

BACKGROUND

It is known that different types of radiation, as well as aging and metabolic disorders, can cause cataract. Several epidemiological investigations show a correlation between cataract development and the dose of ultraviolet radiation (UVR) received. It is well established experimentally that exposure of animal eyes to UVR induces cataract. The purpose of the present study was to determine the dose-response function for UVR-induced opacities in the rat lens after in vivo exposure.

METHODS

Sprague-Dawley rats received 0.1, 0.4, 1.3, 3, 5, 8 or 14 kJ/m2 UVR (lambda MAX = 300 nm, lambda 0.5 = 10 nm) unilaterally for 15 min. At 1 week after exposure both lenses were removed, photographs were taken and the intensity of forward-scattered light was measured.

RESULTS

One week after UVR exposure, opacities occurred on the lens surface, as observed with a microscope. With increased UVR dose the opacities became more intense and occurred also in the equatorial area of the lens, but not in the nucleus. The intensity of forward light scattering increased with increased UVR dose between 3 and 14 kJ/m2. No significant change in intensity of forward light scattering was observed for lower UVR doses.

CONCLUSION

The intensity of forward light scattering in the rat lens increase exponentially with increased UVR dose between 0.1 and 14 kJ/m2.

Physiological insulinemia acutely modulates plasma leptin

Whether insulin acutely regulates plasma leptin in humans is controversial. We examined the dosage-response and time-course characteristics of the effect of insulin on leptin in 10 men (age 42+/-2 years [mean+/-SE]; BMI 29.3+/-2.0 kg/m2). Each individual underwent four 9-h euglycemic clamps (insulin at 20, 40, 80, and 400 mU x m[-2] x min[-1) and a control saline infusion. Although plasma glucose and insulin levels remained constant, leptin diminished from 9.1+/-3.0 to 5.9+/-2.1 ng/ml (P < 0.001) by the end of the control experiment. Conversely, plasma leptin showed a dosage-dependent increase during the insulin infusions that was evident within 30-60 min. The insulin-induced increase in leptin was proportionately lower in obese insulin-resistant men. Free fatty acids (FFAs) decreased during insulin and did not change during saline infusions. ED50 (the dose producing half-maximal effect) for insulin's effect on leptin and FFA was similar (138+/-36 vs. 102+/-24 pmol/l, respectively; P=0.11). To further define the role of physiological insulinemia, we compared the effect of a very low dosage insulin infusion (10 mU x m[-2] x min[-1]) with that of a control saline infusion in another group of 10 men (mean age 39+/-3 years; BMI 27.1+/-1.0 kg/m2). Plasma leptin remained stable during that insulin infusion, but fell by 37+/-2% in the control experiment. Thus physiological insulinemia can acutely regulate plasma leptin. Insulin could mediate the effect of caloric intake on leptin and could be a determinant of its plasma concentration. Inadequate insulin-induced leptin production in obese and insulin-resistant subjects may contribute to the development or worsening of obesity.

Diurnal and ultradian rhythmicity of plasma leptin: effects of gender and adiposity

Plasma leptin shows a nocturnal rise and a pulsatile pattern. This work was undertaken to determine the effects of gender and obesity on this pattern. Twenty-four-hour leptin profiles were evaluated in 31 subjects [17 male, 14 female; age: 36 +/- 2 yr (mean +/- SEM); body mass index: 27.5 +/- 1.0 kg/m2]. Plasma leptin profiles were higher in obese (body mass index > 27 kg/m2) than in lean subjects and higher in women than in men, regardless of fat mass. Leptin showed diurnal rhythmicity with peaks between 2200-0300 (median: 0120) and nadirs between 0800 and 1740 (median: 1033). Spectral analysis revealed 2 components (periodicities: 24 and 12 h) with higher relative amplitudes in lean than in obese subjects. The relative diurnal amplitude also was higher in men than in women, controlling for adiposity. Insulinemia, female sex, and age were negative determinants of diurnal rhythm relative amplitude. Pulse analysis revealed 3.6 +/- 0.3 pulses/24 h, occurring mostly 2-3 h after meals. Pulse frequency correlated negatively with fat mass and insulinemia (Spearman's r = -0.54 and -0.37, respectively; P < 0.05 for each). Thus, obesity is associated not only with higher leptin levels but also with blunted diurnal excursions and dampened pulsatility. This abnormal rhythmicity may contribute to leptin resistance in obesity. The significance of the sexual dimorphism in the diurnal amplitude is unclear, but it may be related to leptin's putative role as a metabolic signal to the reproductive axis.

Bronchiolitis obliterans in a man who used his wood-burning stove to burn synthetic construction materials

Many people heat their homes with wood-burning stoves. However, toxic fire effluent can escape from old or improperly operated stoves. The authors describe a case in which bronchiolitis obliterans developed in a man within hours after he burned synthetic construction materials in his wood-burning stove. Certain factors, such as careless or improper use of the stove, the size of the room, the lack of open-air ventilation and the composition of the materials burned, strongly point to inhalation of the fire effluent as the cause.