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Biomedical subjects

K Ho

Publications and source records attributed to K Ho.

At least 37 records · Page 2Linked to original sources
PubMed1996

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.

Adult↗
PubMed1996

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.

Acute Disease↗
PubMed1996

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.

Adult↗
PubMed1996

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.

Acquired Immunodeficiency Syndrome↗
PubMed1996

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.

Adult↗
PubMed1996

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.

Algorithms↗
PubMed1995

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.

Accidents, Traffic↗
PubMed1995

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)

Amino Acid Sequence↗
PubMed1995

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.

Adolescent↗
PubMed1995

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.

Acute Disease↗
PubMed1994

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.

Adenosine Triphosphate↗
PubMed1994

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+.

Animals↗
PubMed1994

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.

Animals↗