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Biomedical subjects

K Ho

Publications and source records attributed to K Ho.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1993

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.

Adenosine Triphosphate↗
PubMed1993

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.

Amino Acid Sequence↗
PubMed1991

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.

Adolescent↗
PubMed1989

Recovery room oxygenation: a comparison of nasal catheters and 40 per cent oxygen masks.

One hundred and sixty-one ASA physical status I-III patients undergoing elective surgery were evaluated using nasal catheters versus 40 per cent O2 venturi masks. Twenty-one per cent of the patients arrived in the recovery room with hypoxia as measured with a pulse oximeter (SaO2 less than 90 per cent). Fifteen minutes later all patients who arrived hypoxic were well oxygenated on their chosen oxygen therapy. Only one patient that arrived normoxic became hypoxic using a nasal catheter 15 minutes later. There was no statistical difference between patients given 40 per cent O2 by mask versus patients given oxygen by nasal catheter. The mean SaO2 for the group given 40 per cent O2 at 15 minutes was 96.7 +/- 2.15 per cent versus 96.6 +/- 2.48 per cent for nasal catheters. Nasal catheters are as effective as 40 per cent O2 masks for treating hypoxia in the recovery room. Obesity and age were statistically significant risk factors in the patients that arrived hypoxic. Patients were 47.4 +/- 15.6 years in the hypoxic group versus 38.3 +/- 15.6 years in the non-hypoxic group (p less than 0.001). Patients having an endotracheal tube with intermittent positive pressure ventilation or having a premedication were more apt to be hypoxic on arrival. These last two factors were closely associated and may reflect bias. The patient's gender, history of smoking, presence of obstructive lung disease, not including asthma, location of incision, or type of anaesthetic were not statistically significant risk factors.

Adolescent↗
PubMed1989

Prevention of hypothermia during abdominal surgery: comparison of thermal tube and blanket.

Twenty patients who received elective abdominal surgery for more than two hours were randomly assigned into two groups. Group 1 was warmed by using "EXACON" thermal therapy system model TT8200. Group 2 was warmed by using a thermal blanket of aquamatic K-thermia (electronic control), model PK-600 of American Hamilton medical systems. Other variables were kept constant, and the theater temperature was maintained at 24 degrees C. Core temperature was recorded every five minutes in a two hour period. There were statistically significant differences between these two groups intra-operatively. Decrease of temperature between these two groups had significant changes from 30 minutes to 2 hours (p less than 0.05). The warming effect of esophageal thermal tube was well controlled by directly warming the central compartment. However, the effect of blanket was unpredictable due to wet dressing and superficial warming of surgical fields. There were no side effects during the study.

Abdomen↗
PubMed1989

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.

Adult↗