4-Alkylidenyl glutamic acids, potent and selective GluR5 agonists

Twenty-four 4-alkylidene glutamic acids were synthesised and tested as potential subtype selective GluR5 and 6 ligands. It was found that a critical size of alkylidene group gave potent and selective GluR5 receptor agonists. LY339624 had Kis of 0.0326 and >100 microM on GluR5 and 6 receptors, respectively.

Ethnic differences in nocturnal blood pressure decline in treated hypertensives

Lack of a nocturnal decline in blood pressure (BP) has been associated with more severe end organ damage in hypertensives, and blacks appear less likely than whites to have a > 10% drop in nighttime BP ("dipping"). Little information is available about the relationship between treatment regimens, ethnic group classification, and dipping in treated hypertensive patient populations. We obtained 24-h ambulatory BP readings in 438 adult white (n = 103), black (n = 200) and Hispanic (n = 135) treated hypertensives. Tycos monitors were connected in patients' homes before their usual morning medication dose time. Research assistants administered a quality-of-life questionnaire, recorded patients' drug regimen, and observed the patients take their morning dose. Monitors were programmed to record BP every 30 min. Dippers were defined as persons who had a drop of > or = 10% decline in average daytime (08:00 to 22:00) compared to nighttime (00:00 to 04:00) BP. Logistic regression modeling was used to assess the relationship between demographic and treatment variables and probability of dipping. Twenty-four-hour average BP was similar in all three ethnic groups. However, the absence of a systolic dip was significantly more common in black and Hispanic men than in white men (OR black v white = 11.54, 95% CI = 3.92 to 34.01; OR Hispanic v white = 7.32, 95% CI = 2.47 to 21.68). There were no ethnic group differences in probability of systolic dipping among women. Absence of a diastolic dip was approximately twice as common in blacks and Hispanics than in whites, with no marked gender-by-ethnic-group interaction in the magnitude of the association. Of the 10 most commonly prescribed antihypertensives, no single drug was positively associated with nocturnal BP decline. Later versus earlier morning dose time, but not once-a-day dosing, was associated with absence of dipping. Treated black and Hispanic hypertensives are less likely to "dip" than non-Hispanic whites. No particular drug was positively associated with dipping.

Vasorelaxant and antiproliferative effects of berberine

The present study was intended to examine the relaxant effects of berberine in rat isolated mesenteric arteries. Berberine produced a rightward shift of the concentration-response curve to phenylephrine and significantly reduced the maximal contractile response to phenylephrine. Berberine (10(-7)-3x10(-5) M) also relaxed the phenylephrine- and 9,11-dideoxy-11alpha, 9alpha-epoxy-methanoprostaglandin F(2alpha)-precontracted arteries with respective IC(50) values of 1.48+/-0.16x10(-6) and 2.23+/-0. 22x10(-6) M. Removal of a functional endothelium significantly attenuated the berberine-induced relaxation (IC(50): 4.73+/-0. 32x10(-6) M) without affecting the maximum relaxant response. Pretreatment with N(G)-nitro-L-arginine methyl ester (L-NAME) or methylene blue reduced the relaxant effect of berberine, and L-arginine (10(-3) M) partially antagonized the effect of L-NAME. In contrast, pretreatment with 10(-6) M glibenclamide or 10(-5) M indomethacin had no effect. Berberine (10(-5) M) reduced over by 50% the transient contraction induced by caffeine or phenylephrine in endothelium-denuded rings bathed in Ca(2+)-free Krebs solution. Pretreatment with putative K(+) channel blockers, such as tetrapentylammonium ions (1-3x10(-6) M), 4-aminopyridine (10(-3) M), or Ba(2+) (3x10(-4) M), significantly attenuated the berberine-induced relaxation in endothelium-denuded arteries. In contrast, tetraethylammonium ions (3x10(-3) M), charybdotoxin (10(-7) M) or glibenclamide (10(-6) M) were without effect. Berberine reduced the high-K(+)-induced sustained contraction and the relaxant response to berberine was greater in rings with endothelium (IC(50): 4.41+/-0.47x10(-6) M) than in those without endothelium (IC(50): 8.73+/-0.74x10(-6) M). However, berberine (10(-6)-10(-4) M) did not affect the high-K(+)-induced increase of intracellular [Ca(2+)] in cultured aortic smooth muscle cells. Berberine did not affect active phorbol ester-induced contraction in Ca(2+)-free Krebs solution. In addition, berberine inhibited proliferation of cultured rat aortic smooth muscle cells with an IC(50) of 2.3+/-0.43x10(-5) M. These findings suggest that berberine could act at both endothelium and the underlying vascular smooth muscle to induce relaxation. Nitric oxide from endothelium may account primarily for the berberine-induced endothelium-dependent relaxation, while activation of tetrapentylammonium-, 4-aminopyridine- and Ba(2+)-sensitive K(+) channels, inhibition of intracellular Ca(2+) release from caffeine-sensitive pools, or a direct relaxant effect, is likely responsible for the berberine-induced endothelium-independent relaxation. Mechanisms related to either Ca(2+) influx or protein kinase C activation may not be involved. Both vasorelaxant and antiproliferative effects may contribute to a long-term benefit of berberine in the vascular system.

Criteria for cure of acromegaly: a consensus statement

In February 1999, a workshop was held in Cortina, Italy to develop a consensus defining the criteria for cure of acromegaly. The workshop was sponsored by the University of Brescia and hosted by the Italian Society of Endocrinology. Invited international participants included endocrinologists, neurosurgeons, and radiotherapists skilled in the management of acromegaly. This statement summarizes the consensus achieved in these discussions.

Ruptured abdominal aortic aneurysm--outcome in a community teaching hospital intensive care unit

Ruptured abdominal aortic aneurysm (RAAA) is a surgical emergency associated with a high mortality often requiring postoperative intensive care. Our objectives were to assess the outcome of RAAA management in a nontertiary community hospital intensive care unit (ICU) and to compare this with historical data from tertiary hospitals. We also sought to identify variables related to outcome and evaluate the potential of an organ failure score to identify patients at increased risk of death. The study was a retrospective chart review of patients with RAAA over 11 years (1986-1996 inclusive) at Manly District Hospital, a 210 bed community teaching hospital with eight intensive care beds. Forty patients were identified in the study period as having been admitted to ICU after RAAA surgery. There was an overall hospital mortality rate of 47.5% and intensive care mortality rate of 42.5% for successfully operated RAAA. Five variables were significantly different between survivors and non-survivors. These were age, total amount of blood products required, duration of operation, development of hypotension (systolic blood pressure < 90 mmHg) in ICU postoperatively, and APACHE II score at Day 1 ICU. A trend was also found between mortality rate and the number of failed systems after 48 hours intensive care stay. Mortality for a patient with zero failed systems was 38%, one failed system 42%, two 58% and three 67%. Based on these results, management of RAAA in a non-tertiary setting appears appropriate with postoperative care occurring in an ICU where there is adequate equipment and medical and nursing staff experienced in the care of complex critical illness.

Use of bioptic amorphic lenses to expand the visual field in patients with peripheral loss

PURPOSE

To test the effectiveness of a bioptic form of a peripheral vision-enhancement lens in patients with retinitis pigmentosa (RP), choroideremia, and Usher's syndrome Type II.

METHODS

Fifteen patients with peripheral visual field loss were trained in the use of the amorphic lenses for driving and other everyday activities for a 3-month period. A cross-over study design was used, where one group of eight patients received training during the first 3 months of the 6-month study, and another group of seven patients received training during the second 3 months. All patients were administered a battery of clinical, psychophysical, functional, mobility, and driving assessment tests at the beginning of the study, at 3 months, and at 6 months. The assessment tests were coded according to the primary visual skill involved in the task. These visual skills included: recognition, peripheral detection, scanning, tracking, visual memory, and mobility.

RESULTS

After training, the patients showed improvement in all visual skills categories on the assessment tests, with overall improvement of 37%. There was no significant difference in the levels of improvement between the two groups. Those with smaller visual field extents showed significantly greater improvement on peripheral detection and scanning tasks. Those patients trained during the first 3 months of the study maintained their skills when tested at the 6-month point.

CONCLUSION

Patients with peripheral vision loss may benefit from a rehabilitation program which combines low vision training with amorphic lenses in a bioptic configuration.

Assembly of ROMK1 (Kir 1.1a) inward rectifier K+ channel subunits involves multiple interaction sites

The ROMK1 (Kir 1.1a) channel is formed by a tetrameric complex of subunits, each characterized by cytoplasmic N- and C-termini and a core region of two transmembrane helices flanking a pore-forming segment. To delineate the general regions mediating the assembly of ROMK1 subunits we constructed epitope-tagged N-terminal, C-terminal, and transmembrane segment deletion mutants. Nonfunctional subunits with N-terminal, core region, and C-terminal deletions had dominant negative effects when coexpressed with wild-type ROMK1 subunits in Xenopus oocytes. In contrast, coexpression of these nonfunctional subunits with Kv 2.1 (DRK1) did not suppress Kv 2.1 currents in control oocytes. Interactions between epitope-tagged mutant and wild-type ROMK1 subunits were studied in parallel by immunoprecipitating [35S]-labeled oocyte membrane proteins. Complexes containing both wild-type and mutant subunits that retained H5, M2, and C-terminal regions were coimmunoprecipitated to a greater extent than complexes consisting of wild-type and mutant subunits with core region and/or C-terminal deletions. The present findings are consistent with the hypothesis that multiple interaction sites located in the core region and cytoplasmic termini of ROMK1 subunits mediate homomultimeric assembly.

Use of single dose low-molecular-weight heparin in long hemodialysis

Low-molecular-weight (LMW) heparin has recently been used for anti-coagulation in maintenance hemodialysis. The LMW heparin was administered as a single bolus in hemodialysis that usually lasted for four hours or less. The regimen for administering LMW heparin in hemodialysis of longer duration (5 hours or more) is not well documented and manufacturers recommend a supplementary dose equivalent to one-quarter of the initial dose to be given at 4 hours after the commencement of hemodialysis. In this study, we explored whether administering a single dose of LMW heparin is feasible in hemodialysis of longer duration. Maintenance five-hour hemodialysis sessions were performed in nine uremic patients with two different heparin regimens: single dose of LMW heparin (nadroparin) 12,500 ICU AXa at the beginning of dialysis or a priming dose of nadroparin 10,000 ICU AXa at the beginning of dialysis followed by a supplementary dose of nadroparin 2,500 ICU AXa at the beginning of the fifth hour of dialysis. Clots in the airtraps or clotting of the dialyser were not observed in hemodialysis with the single dose heparin regimen. The anti-Xa activities at different time intervals during dialysis were above the therapeutic range of 0.5 U/ml except towards the end of the hemodialysis treatment. There was no difference between anti-Xa activities determined in dialysis sessions using two different regimens of LMW heparin at any individual time interval. The anti-thrombotic effect determined by the area under the time response curve for anti-Xa activity was comparable in the two LMW heparin regimens. Hence, our findings suggest a single bolus dose of LMW heparin (nadroparin) at 12,500 ICU AXa provides adequate, safe, and effective anti-coagulation for five-hour hemodialysis. This practice is convenient and avoids the necessity of administering a double dose of LMW heparin.

The ROMK-cystic fibrosis transmembrane conductance regulator connection: new insights into the relationship between ROMK and cystic fibrosis transmembrane conductance regulator channels

The structure of ATP-sensitive K+ (KATP) channels in excitable cells has been elucidated recently. These channels consist of a pore-forming inward rectifier K+ (Kir) channel and four sulfonylurea receptor proteins. In the distal nephron, Kir 1.1 (ROMK) channels probably contribute to the formation of epithelial (KATP) channels. Current findings suggest the possibility that these renal KATP channels consist of Kir 1.1 channel-CFTR complexes and therefore represent structural analogues of classical KATP channels.

Cellularization in locust embryos occurs before blastoderm formation

In Drosophila intracellular gradients establish the pattern of segmentation by controlling gene expression during a critical syncytial stage, prior to cellularization. To investigate whether a similar mechanism may be exploited by other insects, we examined the timing of cellularization with respect to blastoderm formation in an insect with extreme short-germ development, the African desert locust, Schistocerca gregaria. Using light and electron microscopic techniques, we show that the islands of cytoplasm surrounding cleavage nuclei are largely isolated from their neighbours, allowing cleavage to proceed asynchronously. Within a short time of their arrival at the surface and prior to blastoderm formation, nuclei become surrounded by complete cell membranes that block the free uptake of dye (10,000 kDa) from the yolk. Our results imply that the formation of the blastoderm disc involves the aggregation of cells at the posterior pole of the egg and not the migration of nuclei within a syncytial cytoplasm. These findings suggest that the primary cleavage syncytium does not play the same role in patterning the locust embryo as it does in Drosophila. However, we do identify a syncytial nuclear layer that underlies the forming blastoderm and remains in continuity with the yolk.

An Internet primer, Part II: Tools of the Internet

This article reviews several of the key tools and protocols that physicians use to access information on the internet. They include the World Wide Web, electronic mail, newsgroups, Gopher, and file transfer protocol. A general description of these tools, and some tips and nuances in their application, are discussed. This article is the second in a three-part series, "An Internet Primer."

Smoking, smoking cessation, and understanding of the role of multiple cardiac risk factors among the urban poor

OBJECTIVE

To determine in a population of low socioeconomic status (SES) patients: (a) rates of current smoking and smoking cessation, (b) persons' understanding of the adverse health impact of multiple cardiovascular disease (CVD) risk factors, and (c) if the diagnosis of other CVD risk factors, specifically hypertension or hypercholesterolemia, was related to smoking cessation.

DESIGN

Cross-sectional interview survey.

SETTING

Community clinics and eligibility centers of the Harris County Hospital District (HD), which provides primary care to over 166,000 indigent persons in Houston, Texas.

SUBJECTS

Randomly selected adults attending an HD setting for eligibility screening or primary care.

RESULTS

Over 93% of subjects approached participated (n = 547). Their mean age was 40.7 years, 55% were female, and 39% had > 9 years of education. The ethnic distribution was 54% Hispanic, 28% black, and 14% non-Hispanic white. Current smoking ranged from 10% among Hispanic females to 56% among black males. The percentage of ever smokers who had quit was 24% among black males, 44% among black females, 43% among Hispanic males, and 70% among Hispanic females. The majority recognized the increase in danger from smoking in the presence of hypertension or hypercholesterolemia. Among patients who were smokers when they found out they had hypertension (n = 70), 65% reported it increased their desire to quit. After adjustment for other variables including age and known CVD, predictors of being an ex-smoker were being female (OR 2.1, 95% CI 1.3-3.5), being Hispanic (OR 2.8 95% CI 1.5-5.7), and having hypertension (OR 2.3, 95% CI 1.3-4.2).

CONCLUSION

In this low SES population, there was substantial smoking cessation, widespread acknowledgment of the cumulative effect of smoking and other CVD risk factors, and some evidence that smoking cessation increased after the diagnosis of hypertension.

Use of low-dose low molecular weight heparin in hemodialysis

We investigated the lowest effective dosage of low molecular weight (LMW) heparin for hemodialysis in comparison to unfractionated (UF) heparin. Initial hemodialysis sessions were undertaken in 10 uremic patients with UF heparin of the dose habitually required for each patient. Four-hour hemodialysis sessions were then undertaken with LMW heparin (nadroparin) in a single bolus (200 anti-Xa unit Institut Choay/kg [aXaU IC/kg], 175 aXaU IC/kg, 150 aXaU IC/kg, or 125 aXaU IC/kg; two sessions for each dosage). Anti-Xa levels and activated partial thromboplastin time (APTT) were monitored hourly during dialysis. Fiber bundle volume of dialyzer was measured before and after dialysis. Urea clearance was determined at the onset and completion of dialysis. There were no episodes of excessive bleeding, clotting of dialyzers, or clots in air traps with UF heparin or LMW heparin. A 35% increase in APTT above baseline was observed in all dialysis sessions 1 hour after LMW heparin bolus, but the APTT decreased rapidly thereafter. The anti-Xa levels exceeded 0.5 U/mL for all sessions using LMW heparin irrespective of the dosage. No significant reduction of urea clearance was found in dialysis with either UF or LMW heparin. No reduction of fiber bundle volume of dialyzer was observed in dialysis with either UF or LMW heparin, although a small reduction (3%) was observed in dialysis with LMW heparin at 125 aXaU IC/kg. We concluded that the use of LMW heparin for hemodialysis is safe and effective as compared with UF heparin. The lowest effective dosage can be reduced to 125 aXaU IC/kg in high-risk patients to reduce hemorrhagic complications.

An Internet primer for emergency physicians: Part I

The growth of the popularity of the Internet is nothing short of phenomenal. Increasingly, valuable medical information is becoming available on line for physicians and health consumers alike. Physicians can clearly benefit personally and professionally by obtaining access to the Internet. The purpose of this article is to introduce the Internet to physicians who have limited experience with this new medium. It discusses the concept of the Internet, the necessary computer components and modem for on line connection, and the various types of Internet Service Providers. A glossary is also provided to explain some of the most common terminology used in the Internet culture.

Improving the detection of radiographically occult ankle fractures: positive predictive value of an ankle joint effusion

OBJECTIVE

To assess the value of an ankle effusion on plain radiographs as a predictor of radiographically occult fracture after acute ankle trauma.

PATIENTS

Consecutive patients with acute ankle trauma and radiographic evidence of an ankle joint effusion. Patients were excluded if ankle trauma was sustained more than 48 h previously or if a fracture was visible on initial photographs.

METHODS

All subjects (n = 26) underwent computed tomography (CT) of the ankle in sagittal and coronal planes. Ankle effusion size was measured from initial lateral ankle radiographs.

RESULTS

Twelve patients (46%) had radiographically occult fractures identified with CT. Fracture sites included: posterior or lateral malleoli (n = 4), calcaneus (n = 1), or talus (n = 7). Ankle effusion size was 11.2 mm in the group without fracture and 17.1 mm in the group with fracture (P < 0.0001). The positive predictive value of an effusion 15 mm or greater was 83%. CT detected significant soft-tissue injuries in four (15%) patients including peroneal retinaculum tear (n = 1), anterior talofibular ligament avulsion (n = 1), and tears of the peroneus longus (n = 1) and tibialis posterior (n = 1) tendons.

CONCLUSIONS

The presence of a large ankle effusion of radiographs after acute ankle trauma suggests an underlying fracture. An ankle effusion of > or = 15 mm is a reasonable threshold to prompt additional imaging. Computed tomography provides good visualization of subtle bone injuries and may detect clinically imported soft-tissue injuries.

Acute care of myocardial infarction

Patients with acute myocardial infarct (AMI) need rapid diagnosis and prompt initiation of thrombolytic therapy. Patients with suspected cardiac ischemia must receive a coordinated team response by the emergency room staff including rapid electrocardiographic analysis and a quick but thorough history and physical examination to diagnose AMI. Thrombolysis and adjunct therapies should be administered promptly when indicated. The choice of thrombolytics is predicated by the location of the infarct.

Occult ankle fracture detected by an ankle effusion on plain radiography: a case report

Subtle ankle fractures may escape detection on plain radiography. These occult fractures can cause prolonged disability and pain. We present a case of blunt ankle trauma where plain radiography failed to reveal any bony abnormalities. The recognition of an ankle effusion on plain radiographs prompted us to perform a computed tomography (CT) scan of the ankle. The CT scan demonstrated an anterior plafond fracture of the distal tibia, which required surgical fixation. Had the fracture not been identified, our patient would have been treated inappropriately for a ligament sprain. An occult fracture should be suspected if an ankle is grossly swollen after blunt trauma, and plain radiography demonstrates an effusion. In this circumstance, performance of further imaging studies, such as conventional or CT, are advised to rule out an occult ankle fracture.

Pediatric AIDS and advanced directives: a three-year prospective study in New York State

Most HIV-infected families currently receive their care in an ambulatory setting. Ambulatory care provides greater means of medical care, and planning for the infected family members. Advanced Directives (AD) and Do Not Resuscitate (DNR) for adults are now discussed in an ambulatory setting rather than under the duress of a hospital admission. We felt it is important to examine the practice of discussing AD/DNR with the families of pediatric AIDS patients in an out patient setting. Twenty-one and 26 AIDS-designated centers in New York State and five major hospitals in New York City were contacted through a telephone survey in 1991 and 1994, respectively. Questions were designed to obtain demographics of the hospital, pediatric AIDS population, and their DNR/AD policies. In 1991 and 1994, the survey was conducted with the pediatric unit of hospitals with pediatric AIDS. In 1991, only 12 (75%) hospitals had an existing policy on pediatric DNR. No hospital had admitted a patient with AD/DNR obtained as an outpatient, nor were there guidelines at any hospital to approach the issue in an outpatient setting. In 1994, 20 (95%) hospitals had a DNR policy for pediatric patients. We found that even though six patients were admitted with AD obtained as outpatients, no outpatient guidelines existed for AD/DNR for pediatrics. The number of cases of pediatric AIDS in New York State increased by 29.7% for the 1991-1994 period. While pediatric DNR existed in 1991/1994, we found there were presently no guidelines for obtaining AD/DNR for pediatric AIDS patients in an ambulatory setting. Families infected with HIV should have a caring atmosphere to help them address pediatric AD/DNR with their primary care providers. However, we believe that guidelines should be developed to address this issue.

Using tomography to diagnose occult ankle fractures

STUDY OBJECTIVES

To determine the incidence of occult ankle fractures and to determine whether an ankle effusion identified radiographically correlated with the presence of an occult fracture.

METHODS

Attending physicians in the emergency department of a university hospital prospectively identified patients with acute ankle injuries that produced ecchymosis or edema over two or more major ligaments of the ankle. Plain radiographs of these patients demonstrated ankle effusions without fractures. A consecutive sample of patients with acute ankle injuries was selected. Thirty-six of 1,151 patients were eligible to enter the study; 2 of these patients subsequently were excluded from the data analysis. All eligible patients underwent plain ankle tomography at 3-mm intervals in the coronal and sagittal planes. The types and frequencies of occult ankle fractures identified on plain film tomography were noted. The distention of the ankle joint capsule of enrolled patients was measured to determine if the degree of effusion correlated with the presence of an occult fracture.

RESULTS

The minimum incidence of occult fractures in the general population with ankle injuries was 1%. Twelve of 34 patients (35%) with acute, severe injuries had occult fractures. Depending on the size, an effusion was correlated with the presence of an occult fracture in 35% to 85% of the study population.

CONCLUSION

Plain film tomography should be used when evaluating ankle injuries if both edema or ecchymosis over two or more stabilizing ligaments and radiographic evidence of an effusion are present simultaneously.

Attitudes towards mental patients in Hong Kong

The purpose of this survey was to understand how the people of Hong Kong perceive mental health, mental illness, mental patients and mental health facilities. In March 1994, a total of 1,043 successful telephone interviews were conducted out of 2,202 valid telephone numbers. The sample was found to be representative of the Hong Kong adult population in terms of sex ratio, age structure, educational achievement and economic status. It was found that the majority of people of Hong Kong were very concerned about their mental health. Their knowledge on mental health was fairly good. Their attitudes towards mental patients and mental health facilities were, however, quite negative. Unlike previous western findings, these views towards mental patients and their rehabilitation facilities were found to be weakly associated with socio-economic factors including age, educational level and household income.

Acute mesenteric ischemia in a middle-aged patient: case report and discussion

Mesenteric ischemia usually occurs in elderly patients, especially those with predisposing factors. It has also been described in young patients using oral contraceptive pills or illicit drugs. We present a case of a middle-aged woman who developed acute focal ischemia of the small intestine without predisposing factors. The unusual presentation of this patient, combined with her relative youth, obscured the diagnosis, which was ultimately made at laparotomy. The diagnosis of mesenteric ischemia should be considered in patients of any age presenting with recurrent or severe abdominal pain, particularly when no alternative cause is apparent. The definitive study to diagnose mesenteric ischemia is angiography. Unless identified early in its course, the condition may progress to frank infarction with a significant increase in morbidity and mortality. Because of this, an aggressive approach to the diagnosis and therapy of mesenteric ischemia is essential.

Emergency management of acute adult asthma

Despite advances in understanding the pathophysiology of acute asthma and the development of new, effective therapies, patients still die. While physicians agree that most asthma deaths could be prevented if patients were treated adequately, evidence suggests that both patients and physicians continue to underestimate the severity of asthma attacks and delay adequate treatment.

A comparison of driving in older subjects with and without age-related macular degeneration

OBJECTIVE

To determine the effects of age and central vision loss on driving skills.

METHODS

Ten subjects with age-related macular degeneration and average binocular visual acuity of 20/70, and 11 age-similar subjects with normal vision, were examined with a battery of cognitive and visual tests, an interactive driving simulator, and an on-road driving test. Data were collected on the frequency of real-world accidents and convictions for traffic violations.

RESULTS

There were no significant differences between the two groups on any of the cognitive tests. The age-related macular degeneration group demonstrated poorer performance on the driving simulator, including delayed braking response times to stop signs, slower speeds, and more of both lane boundary crossings and simulator accidents. The age-related macular degeneration group also demonstrated poorer overall on-road test performance, including having significantly more points deducted for driving too slowly and for not maintaining proper lane position. However, these effects on the simulator and the on-road test did not translate into an increased risk of real-world accidents for the age-related macular degeneration group. Significantly more control subjects than patients with age-related macular degeneration were involved in self-reported accidents, and significantly more control subjects had state convictions for traffic violations. There was evidence of compensation in the age-related macular degeneration group in four major areas: (1) not driving in unfamiliar areas; (2) traveling at slow speeds; (3) self-restricting their nighttime driving, and (4) taking fewer risks while driving (eg, not changing lanes). There was also evidence of compensation in the older control group.

CONCLUSIONS

Vision, simulator, and on-road test variables combined with subjective risk taking predicted self-reported real-world accidents in a logistic regression analysis. However, risk taking, rather than simulator or road-test performance, was the most significant predictor for both patients with age-related macular degeneration and the control group.

ROMK inwardly rectifying ATP-sensitive K+ channel. II. Cloning and distribution of alternative forms

The rat ROMK gene encodes inwardly rectifying, ATP-regulated K+ channels [K. Ho, C. G. Nichols, W. J. Lederer, J. Lytton, P. M. Vassilev, M. V. Kanazirska, and S. C. Hebert. Nature Lond. 362: 31-38, 1993; H. Zhou, S. S. Tate, and L. G. Palmer. Am. J. Physiol. 266 (Cell Physiol. 35): C809-C824, 1994], and mRNA encoding these channels is widely expressed in distal cortical and outer medullary nephron segments [see companion study; W.-S. Lee and S. C. Hebert. Am. J. Physiol. 268 (Renal Fluid Electrolyte Physiol. 37): F1124-F1131, 1995]. Using approaches based on homology to ROMK1, we have identified two additional ROMK isoforms, ROMK2b and ROMK3. Analysis of the nucleotide sequences of the ROMK isoforms indicates that molecular diversity of ROMK transcripts is due to alternative splicing at both the 5'-coding and 3'-noncoding regions. The splicing at the 5' end of ROMK gives rise to channel proteins with variable-length NH2 termini containing different initial amino acid sequences. Functional expression of these isoforms in Xenopus oocytes showed that they form functional Ba(2+)-sensitive K+ channels. The nephron distribution of mRNAs encoding alternatively spliced isoforms of ROMK (ROMK1-ROMK3) was investigated by reverse transcription-polymerase chain reaction (RT-PCR) of nephron segments dissected from rat kidney. Nondegenerate PCR primer pairs were designed to span at least one intron and to amplify specific alternatively spliced forms of ROMK.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of radiographically occult ankle fractures following acute trauma: positive predictive value of an ankle effusion

OBJECTIVE

The purpose of our study was to determine if the presence of an ankle effusion on plain radiographs after acute ankle trauma is predictive of occult ankle fracture when no fracture is visible on the standard radiographic series.

SUBJECTS AND METHODS

The ankle radiographs of 1153 patients with acute ankle trauma were examined for fracture and for the presence and extent of anterior and posterior capsular distension. Patients with ankle effusions but no detectable fracture subsequently underwent sagittal and coronal complex-motion tomography.

RESULTS

Eleven of 33 patients with ankle effusions and otherwise normal plain radiographs had occult fractures identified with tomography. The fracture sites were as follows: osteochondral fracture of talar dome (n = 4), neck of talus (n = 1), medial malleolus (n = 1), anterior tibial rim (n = 1), posterior tibial rim (n = 1), tibial plafond (n = 1), lateral malleolus (n = 1), and anterior process of calcaneus (n = 1). The radiographic size of an ankle effusion was predictive of occult fracture. An ankle effusion measuring 13 mm or more in anterior plus posterior capsular distension had an 82% sensitivity and 91% specificity for underlying fracture in our series. The positive predictive value of an ankle effusion 13 mm or greater was 82%.

CONCLUSION

The presence of an ankle effusion on plain radiographs following acute ankle trauma is suggestive of an underlying fracture. An ankle effusion of 13 mm or greater in total capsular distension has a positive predictive value of 82% for occult fracture and is a reasonable threshold to prompt additional imaging.

Regulation of ROMK1 K+ channel activity involves phosphorylation processes

An inwardly rectifying, ATP-regulated K+ channel with a distinctive molecular architecture, ROMK1, was recently cloned from rat kidney. Using patch clamp techniques, we have investigated the regulation of ROMK1 with particular emphasis on phosphorylation/dephosphorylation processes. Spontaneous channel rundown occurred after excision of membrane patches into ATP-free bath solutions in the presence of Mg2+. Channel rundown was almost completely abolished after excision of patches into either Mg(2+)-free bathing solutions or after preincubation with the broad-spectrum phosphatase inhibitor, orthovanadate, in the presence of Mg2+. MgATP preincubation also inhibited channel rundown in a dose-dependent manner. In addition, the effect of the specific phosphatase inhibitors okadaic acid (1 microM) and calyculin A (1 microM) was also investigated. The presence of either okadaic acid or calyculin A failed to inhibit channel rundown. Taken together, these data suggest that rundown of ROMK1 involves a Mg(2+)-dependent dephosphorylation process. Channel activity was also partially restored after the addition of MgATP to the bath solution. Addition of exogenous cAMP-dependent protein kinase A (PKA) catalytic subunit led to a further increase in channel open probability. Addition of Na2ATP, in the absence of Mg2+, was ineffective, suggesting that restoration of channel activity is a Mg(2+)-dependent process. Addition of the specific PKA inhibitor, PKI, to the bath solution led to a partial, reversible inhibition in channel activity. Thus, PKA-dependent phosphorylation processes are involved in the modulation of channel activity. This observation is consistent with the presence of potential PKA phosphorylation sites on ROMK1.

Differential expression of the inwardly-rectifying K-channel ROMK1 in rat brain

We have investigated the distribution of the inwardly-rectifying K-channel ROMK1 in rat brain using Northern blotting and in situ hybridization. High levels of expression were found in cortex and hippocampus but not in substantia nigra, ventromedial hypothalamus, cerebellum or striatum. PCR primers generated against ROMK1 amplified a 300 bp cDNA fragment from cortex and hippocampus identical in sequence to ROMK1.

Mg(2+)-dependent inward rectification of ROMK1 potassium channels expressed in Xenopus oocytes

1. ROMK1 potassium channel currents were examined in Xenopus oocytes by two-microelectrode voltage-clamp and patch-clamp techniques following injection of oocytes with in vitro transcribed ROMK1 cRNA. Macroscopic currents recorded from intact cells rectified inwardly at positive potentials. 2. In inside-out membrane patches rectification is manifested as an apparent reduction of single channel current (at 500 Hz) in the presence of 0.1-10 mM Mg2+, without a decrease in the channel open probability. No inward rectification is observed when membrane patches are isolated into solutions containing potassium as the only internal inorganic cation. 3. Mg2+ block can be described by a simple one-site model for Mg2+ binding with K0 ([Mg2+] causing half-maximal block at 0 mV) of 16.7 mM and delta (the fraction of the membrane field sensed by the blocking Mg2+) of 0.35. 4. The voltage dependence of channel block by cytoplasmic Mg2+ was shifted approximately -50 mV by a reduction in extracellular [K+] from 140 to 0 mM, corresponding to a decrease of K0 to 4.4 mM. 5. At negative membrane potentials, ROMK1 channels exhibit a single subconducting state that is approximately 4/10 of the full conductance. The incidence of subconductance states is not appreciably enhanced in the presence of Mg2+.

Cholesterol-related knowledge, attitudes, and behaviors in a low-income, urban patient population

To determine knowledge, attitudes, behaviors, and self-reported cholesterol measurement in a low-income, urban patient population, we conducted an interview survey of users and potential users of primary care services in a public health care system for low-income Harris County, Texas, residents. The response rate was 93%, with a final sample of 547 randomly selected subjects 18 years of age and older, who were Hispanic (54%), black (28%), non-Hispanic white (14%), and Asian, Native American, or other (4%). Results indicated that 76% had heard of serum or blood cholesterol, and 30% reported past cholesterol measurement. Knowledge that dietary saturated fat can raise blood cholesterol ranged from 11% in Hispanic men to 51% in non-Hispanic white men and women. A lower percentage of Hispanics correctly answered all knowledge questions, and Hispanics reported higher-fat food choices than blacks and non-Hispanic whites. More than 90% of the respondents expressed interest in more information on diet, 60% reported that they read nutrition labels, and 15% said they have been trying to reduce blood cholesterol levels. A lower percentage of Hispanics reported previous cholesterol measurement than blacks or non-Hispanic whites, a difference that persisted after adjusting for multiple factors associated with cholesterol measurement. Older age (older than 50) and more physician visits in the past year also were associated with past cholesterol measurement. Comparisons with national surveys show that cholesterol knowledge and actual measurement in this low-income sample lag behind those of the national population. Yet, despite gaps in knowledge and cholesterol measurement, respondents showed positive attitudes about and interest in cholesterol-lowering interventions.

Characterization of the major locus of immediate-early genes of rat cytomegalovirus

A major locus of rat cytomegalovirus (RCMV) immediate-early (IE) RNA transcription was identified. A cDNA library from rat embryo fibroblasts infected with RCMV under IE conditions was constructed and screened by using appropriate RCMV DNA probes, revealing at least two IE genes (IE1 and IE2) transcribed from this locus by differential splicing. The first three exons (the first is noncoding) are spliced to exon 4 to form IE1 and to exon 5 to form IE2. The structural organization of the RCMV major IE region is therefore similar to that of human cytomegalovirus (HCMV) and murine cytomegalovirus (MCMV). When we compared the predicted amino acid sequences of the IE1 proteins of RCMV, HCMV, and MCMV, no areas of homology were found across all three proteins, while a few small areas of homology were found between RCMV IE1 and MCMV IE1. In contrast, large areas of homology were found across the carboxyl half of RCMV IE2, HCMV IE2, and MCMV ie3 proteins. In addition, similarities were found at the beginning of exon 5 of RCMV and MCMV. The possible significance of these conserved regions is discussed. Dinucleotide frequency analysis demonstrated a decrease in CpG frequency over the IE region. The IE gene products were able to transactivate heterologous promoters.

Cloning and expression of an inwardly rectifying ATP-regulated potassium channel

A complementary DNA encoding an ATP-regulated potassium channel has been isolated by expression cloning from rat kidney. The predicted 45K protein, which features two potential membrane-spanning helices and a proposed ATP-binding domain, represents a major departure from the basic structural design characteristic of voltage-gated and second messenger-gated ion channels. But the presence of an H5 region, which is likely to form the ion conduction pathway, indicates that the protein may share a common origin with voltage-gated potassium channel proteins.

Anticardiolipin antibodies and lupus anticoagulant in Chinese patients with systemic lupus erythematosus

Ninety-one consecutive patients with systemic lupus erythematosus (SLE) were studied. Forty-two patients had positive anticardiolipin antibodies (aCl) 40 aCl-IgG (44.4%); 4 aCl-IgA (4.4%); 1 aCl-IgM (1.1%). One patient had both aCl-IgG and aCl-IgA and 1 patient had aCl-IgG, aCl-IgA and aCl-IgM. Ten patients (11.1%) had lupus anticoagulant (LA). Both aCl isotypes and LA had no statistical association with thrombosis or thrombocytopenia.

The effect of low dose intravenous lidocaine in tracheal intubation with atracurium

This study investigated the effect of low dose intravenous lidocaine during tracheal intubation with atracurium. Forty patients were studied in double blind, randomized groups. Intravenous lidocaine, 1 mg/kg, or saline was given to the patients three minutes before induction. This result showed there is no difference about the intubation condition between these groups. The changes in mean arterial blood pressure and heart rate after laryngoscopy and intubation were similar in both groups. However, the lidocaine group had a shorter time to have 75% twitch depression (when the first twitch of train of four equals 25% of the original height) than the control group (p less than 0.05). The addition of intravenous lidocaine 1 mg/kg during induction has no significant advantage although it can shorten the intubation time.