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Biomedical subjects

T C Kao

Publications and source records attributed to T C Kao.

At least 37 records · Page 2Linked to original sources
PubMed1994

Effect of anemia on survival of myocutaneous flaps in the pig.

The decision to transfuse patients after major head and neck reconstructive surgery has been influenced by the dictum that a hematocrit level of 30% or more is necessary for the survival of surgical flaps. Pedicled myocutaneous flaps are among the most frequently used methods of reconstruction after major head and neck oncologic surgery. No studies have addressed the survival of myocutaneous pedicled flaps in anemic animals. In this study survival of latissimus dorsi myocutaneous flaps in pigs was evaluated in anemic and control groups. A total of 26 pigs were randomly divided into two groups. The pigs in the anemic group were exsanguinated to normovolemic anemia (average hematocrit, 19%), followed by elevation of a latissimus dorsi myocutaneous flap. In the control group the same operation was performed without exsanguination. All other variables were kept constant. The flap survival was judged on postoperative days 3, 7, and 14 by two evaluators. Ten pigs from each group were found to have 100% flap survival on post-operative day 14. There was no significant difference in mean flap survival rates between two groups for postoperative days 3, 7, and 14. It is concluded that normovolemic anemia does not adversely affect the survival of the myocutaneous flaps. This finding may save unnecessary transfusions in postoperative patients.

Anemia↗
PubMed1994

Comparison of sequential, random, and hemacytometer methods for counting Cryptosporidium oocysts.

In animal and clinical studies of Cryptosporidium infection, counting Cryptosporidium oocysts in collected fecal samples is often critical to interpretation of results and validity of statistical analyses. In this experiment, 3 methods of counting oocysts derived from feces of infected mice were compared. These included sequential counting of oocysts in 25 adjacent microscopic fields, random counting of oocysts in 25 scattered microscopic fields, and hemacytometer counting of oocysts using standard procedures. Numerical results are expressed as the numbers of oocysts per microscopic field for sequential and random counting methods or per microliter for the hemacytometer method. Our results showed that the numbers of oocysts adjusted for volume and weight, or for volume alone, were similar for all 3 techniques. Linear relationships between the 3 methods allow use of linear regression to convert the number of oocysts counted by 1 method into those counted by another. This suggests that comparisons between different experiments in which Cryptosporidium oocysts are counted using any of these methods are both possible and valid.

Animals↗
PubMed1993

An assessment of the efficacy of in situ hybridization as a quantitative method by variance components estimation.

One serviceable feature of in situ hybridization is its potential for assessing relative levels of mRNA in specific regions of tissues and organs. To determine its efficacy as a quantitative technique, we applied a nested factorial design to a multifactorial experiment. Estimates of the magnitude of variance components then allowed an assessment of variation over samples of sections from the same tissue source, variation in label over 2 anatomical sites within the same section of tissue, as well as experiment-to-experiment variation. We found approximately 51% of the total variance arose from experiment-to-experiment variation, while approximately 21% of the total variance was due to variation in autoradiography grain density over neurons in the same brain region. Rat-to-rat variation accounted for approximately 11%. About 10% of the variance was due to variation between sections of tissue that were derived from the same tissue source and were hybridized in the same hybridization experiment. Variation between 2 homologous, bilaterally located brain regions located on the same tissue section (the right and left supraoptic nucleus), accounted for approximately 5% of the total variance. The remaining unaccounted error variance was approximately 2% of the total variance. Since an expected change in cellular content of a particular mRNA was observed as a function of experimental treatment, results suggest in situ hybridization is a useful quantitative method.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Recombinant immunoblot assays for hepatitis C in human immunodeficiency virus type 1-infected US Navy personnel.

The prevalence of hepatitis A, B, C, and D viruses was studied in 467 military personnel with human immunodeficiency virus type 1 (HIV-1) infection. Antibody to hepatitis C virus (anti-HCV) by first-generation ELISA was found in 136 (29%). Of sera repeatedly reactive for anti-HCV by first-generation ELISA, two-antigen recombinant immunoblot assay (RIBA) was positive in 41 (32%) and four-antigen RIBA was positive in 55 (41%). Four-antigen RIBA was positive in 33 (30%) of the 109 with an OD on ELISA of < or = 2.0 compared with 22 (81%) of the 27 with an OD > 2.0 (P < .001). Anti-HCV detected by four-antigen RIBA was associated with increasing age, black or Hispanic race, and antibody to hepatitis B core antigen. When patients with hepatitis B surface antigen were excluded, elevated alanine aminotransferase was found in 5 (8%) of 63 with a negative RIBA and 13 (28%) of 47 with a positive RIBA (P = .006). While RIBA was negative in more than half of those with anti-HCV by ELISA, 55 (12%) of these HIV-1 infected personnel had anti-HCV detected by RIBA, which was associated with a strong reaction by ELISA, elevated liver enzymes, coinfection with hepatitis B, minority race, and older age.

AIDS-Related Opportunistic Infections↗
PubMed1993

Back pain after epidural anesthesia with chloroprocaine.

BACKGROUND: Chloroprocaine has been associated with severe back pain after epidural anesthesia. Factors proposed to contribute to this problem are: 1) the preservative disodium ethylenediaminetetraacetic acid (EDTA), 2) large volumes of chloroprocaine, 3) low pH of chloroprocaine, and 4) local infiltration with chloroprocaine. METHODS: Using a prospective, balanced, randomized study design, 100 patients aged 18-65 yr who were undergoing outpatient knee surgery during continuous epidural anesthesia received one of five local anesthetics (all containing epinephrine 1:200,000). Group I received a bolus of 30 ml 2% lidocaine, followed by 10 ml every 45 min. Group II received 15 ml of 3% chloroprocaine (containing EDTA), plus 5 ml every 45 min. Group III received 30 ml of 3% chloroprocaine plus 10 ml every 45 min. Group IV received 30 ml of 3% chloroprocaine (containing metabisulfite as the preservative but no EDTA) plus 10 ml every 45 min. Group V received 30 ml of 3% chloroprocaine with the pH adjusted to 7.3, plus 10 ml every 45 min. After the anesthesia dissipated and before any analgesic agents were given, the patients were asked to rank maximum knee and back pain on a visual analog scale (0-10) and to give a description of back pain. A telephone interview was conducted 24 h after surgery to determine if back pain returned. Back pain scoring was assessed using a verbal analog scale. RESULTS: After dissipation of anesthesia, the back pain reported by patients fell into two distinct categories. Type 1 pain was described commonly as superficial and localized to the site of needle insertion. There was no difference among groups in incidence of type 1 pain. Type 2 pain was described as deep, aching, burning, and poorly localized in the lumbar region (5% of the patients in group I, 10% in groups II and IV, 50% in group III, and 25% in group V). The incidence of type 2 pain was significantly greater in group III than in groups I, II, or IV. Group III also had a significantly greater mean visual analog scale pain score (types 1 and 2) than all other groups. CONCLUSIONS: Large doses (> or = 40 ml) of chloroprocaine containing EDTA resulted in a greater incidence of deep burning lumbar back pain. Using 25 ml or less of the same solution resulted in an incidence of both types 1 and 2 postepidural anesthesia back pain similar to that in the lidocaine control group.

Adolescent↗
PubMed1993

Does the choice of local anesthetic affect the catecholamine response to stress during epidural anesthesia?

BACKGROUND: Previous work has established that 2-chloroprocaine epidural anesthesia has no effect on circulating plasma epinephrine concentrations in young, healthy, resting volunteers, and results in a decrease in norepinephrine concentration only when a level of analgesia to pinprick of C-8 is reached. The current study was performed to evaluate the possibility that this finding is unique to 2-chloroprocaine. METHODS: Nine healthy volunteers were studied on three occasions at least 48 h apart; each received three local anesthetics (0.75% bupivacaine, 2% lidocaine, and 3% 2-chloroprocaine, all without epinephrine). After placement of lumbar epidural and central venous catheters, blood samples were drawn from the central venous catheter at the following stages: (1) 20 min after catheter placement (baseline), (2) during the first cold pressor test (CPT; hand held in an ice water bath for 90 s), (3) 20 min after reaching epidural analgesia to T-1 level of analgesia, and (4) during a second CPT (epidural analgesia to T-1). Monitoring consisted of noninvasive cardiac output (impedance), noninvasive blood pressure, and EKG. RESULTS: Extensive epidural block (stage 3) altered measured variables only minimally with respect to resting baseline state. During stage 2 (first CPT), mean arterial pressure (MAP), heart rate (HR), cardiac index (CI), epinephrine, and norepinephrine increased. During stage 4 (second CPT), increases in HR and CI were not attenuated by any of the three local anesthetics. Increases in MAP were attenuated by epidural anesthesia with all three local anesthetics. Bupivacaine and 2-chloroprocaine epidural anesthesia significantly attenuated increases in plasma catecholamines, but lidocaine epidural anesthesia did not. CONCLUSIONS: Epidural anesthesia with all three local anesthetic agents tested resulted in an incomplete sympathectomy in the resting state in healthy young men, judged by plasma catecholamine concentrations and cardiovascular variables minimally changed from resting baseline. Lidocaine epidural anesthesia did not attenuate the catecholamine response to CPT, indicating decreased blockade of sympathetic efferent neural traffic compared with bupivacaine and chloroprocaine epidural anesthesia.

Adult↗
PubMed1993

Redistribution of sufentanil to cerebrospinal fluid and systemic circulation after epidural administration in dogs.

Due to its higher lipid solubility, sufentanil may be less likely than morphine to migrate rostrally in the cerebral spinal fluid (CSF) and cause delayed respiratory depression following epidural administration. However, early respiratory depression has been reported in patients after relatively large doses of epidural sufentanil. This has been attributed to systemic drug uptake. We used a dog model to investigate the pharmacokinetics and rostral spread of epidural sufentanil in CSF. Sampling catheters were placed in the lumbar subarachnoid space, the cisterna magna, and femoral arteries of six mongrel dogs. Samples of cisternal CSF, lumbar CSF, and blood were drawn at 0, 1, 5, 15, 30, 60, 90, 120, and 180 min after lumbar epidural sufentanil injection. We measured sufentanil concentrations by gas chromatography-mass spectrometry and used the least squares method to a fit tri-exponential function to each sufentanil concentration versus time data set. Paired t-test was used to test for statistical significance. After epidural sufentanil, lumbar CSF concentrations were significantly higher than plasma or cisternal CSF sufentanil concentrations at all assessment times. Sufentanil concentrations were significantly higher in cisternal CSF than in plasma at 30 and 60 min after injection. Sufentanil appeared rapidly in lumbar CSF, reaching a maximum concentration (Cmax) of 57 ng/mL at 6.5 min. In cisternal CSF, a Cmax of 1.2 ng/mL was reached at 21 min, and Cmax in plasma was 0.35 ng/mL at 6 min. The area under the concentration-time curve (AUC) of sufentanil in cisternal CSF was approximately six times higher than the plasma AUC (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Photic maculopathy after extracapsular cataract surgery. A prospective study.

Photic retinal injuries have been described after surgical exposure to the intense illumination systems of operating microscopes. The overall incidence of such injuries has been postulated at less than 10%. The authors prospectively studied 43 consecutive patients to determine the incidence of photic macular injuries during cataract surgery. Patients underwent complete ophthalmic examinations, fundus photography, and oral fluorography before and after surgery. Photic macular injuries developed in 12 of 43 eyes (28%) as a result of intraocular surgery. This incidence is much higher than previous estimates. The association with possible risk factors, cystoid macular edema, and the effect of these injuries on final visual acuity are discussed.

Cataract Extraction↗
PubMed1992

Analyzing the effect of prenatal care on pregnancy outcome: a conditional approach.

We used vital statistics data to examine the effect of the time of entry into prenatal care relative to the gestational age of delivery on pregnancy outcome. Early entry into prenatal care was associated with better outcomes only in women who delivered at 37 through 42 weeks of gestation. We are concerned that the evaluation of the effect of prenatal care using vital statistics data may be questionable because of the problems inherent in the data.

Bias↗
PubMed1992

The clinicopathological implication of myocytes with contraction bands in autopsy hearts. Quantitative analysis of myocytes with contraction bands in autopsy hearts.

To define the normal extent of myocytes with contraction bands, 51 adult autopsied hearts including 30 normal and 21 common hypertrophic hearts were studied. Based on the histologic features, contraction bands were divided into mild and severe types. They were found in 48 and 32 of the total 51 cases, respectively. However, in five hearts, myocytes with contraction bands were more diffused or localized in one part of the ventricular wall. There were no special different treatments before death among the five cases or others. They seemed however to correlate with sudden death or acute cerebral damages. Therefore, reperfusion injury and metabolic cell injuries were considered. If these 5 cases were excluded, the normal extend of myocytes with contraction bands was considered as less than a 1.7% area in the mild type and a 0.5% area in the severe type found in the ventricular wall. These mild and severe contraction bands were considered related to autolysis or events occurring before death.

Adult↗
PubMed1991

Cryptosporidium infection in an adult mouse model. Independent roles for IFN-gamma and CD4+ T lymphocytes in protective immunity.

Cryptosporidium is a protozoan parasite that can cause chronic life-threatening diarrhea in immunocompromised persons. Host immune responses are poorly understood, an impediment to development of effective therapy. In mice, normal adult BALB/c animals resist infection whereas chronic symptomatic cryptosporidiosis develops in adult nude mice and in neonatally infected BALB/c mice treated with anti-CD4 mAb. To define further the immune defects that allow mice to be infected with Cryptosporidium, adult BALB/c mice were treated with cytolytic anti-CD4 or anti-CD8 or with neutralizing anti-IFN-gamma or anti-IL-2 mAb. Chronic infection, manifested by continuous shedding of sparse but statistically significant numbers of oocysts, occurred with anti-CD4 +/- anti-CD8 mAb treatment although anti-CD8 mAb treatment alone did not allow infection. Treatment with anti-IFN-gamma mAb greatly enhanced oocyst shedding but infection was self-limited. Treatment with a combination of anti-CD4 and anti-IFN-gamma mAb permitted both chronic infection and shedding of large numbers of oocysts. Furthermore mice treated initially with anti-CD4 mAb showed a substantial increase in oocyst shedding when later treated with anti-IFN-gamma mAb; and mice treated initially with both mAbs showed a decline in oocyst shedding when anti-IFN-gamma mAb was stopped. Anti-IFN-gamma mAb treatment of congenitally athymic adult BALB/c mice led to an approximately a 75-fold increase in oocyst shedding. Treatment of adult BALB/c mice with anti-IL-2 mAb did not permit Cryptosporidium infection. These results suggest that redundant immunologic mechanisms limit Cryptosporidium infection such that both CD4+ cells and IFN-gamma are required to prevent initiation of infection whereas either alone can limit the extent (IFN-gamma) or duration (CD4+ T cells) of infection. They also suggest that production of IFN-gamma by a non-T cell contributes to host immunity.

Analysis of Variance↗
PubMed1991

Changes in human plasma catecholamine concentrations during epidural anesthesia depend on the level of block.

To test the hypothesis that increasing levels of epidural analgesia will produce progressive decreases in circulating catecholamines, we sequentially produced three levels of analgesia, T8, T4, and C8, to pin prick in young, healthy volunteers. Three percent chloroprocaine (plain) was used as the local anesthetic. The epidural analgesia was allowed to dissipate following the T8 and T4 levels of block. After the C8 level the block was reinforced to study the effect of a "top-up" dose. Blood samples were drawn from a central venous catheter. Plasma concentrations of norepinephrine and epinephrine were determined by the single isotope radioenzymatic method. Despite extensive block, hemodynamic alterations were minimal, and no significant decrease in plasma epinephrine was observed as the level of analgesia was raised to the C8 dermatome. When the level of analgesia was raised above T8, there was a trend for norepinephrine to decrease, but this decrease did not become statistically significant until analgesia reached the C8 dermatome. Reinforcing the epidural block at the C8 level of analgesia resulted an insignificant decrease in epinephrine and norepinephrine NE. Under the conditions of the present study, epidural block with a sensory analgesia level as high as C8 did not significantly decrease the plasma concentration of epinephrine in unstressed volunteers. The plasma concentration of norepinephrine significantly decreased only when the level of sensory analgesia was approximately C8.

Adult↗
PubMed1986

Pathology of Kawasaki disease in the healed stage. Relationships between typical and atypical cases of Kawasaki disease.

To define the pathological features of Kawasaki disease (KD) in the healed stage (over 40 days of illness), 69 autopsied infants with clinically typical KD (25 in the healed stage and 38 in the acute stage) and atypical KD (four in the healed stage and two in the acute stage) were examined. In the medium-sized arteries with coronary aneurysm in KD, panvasculitis was evident in the acute stages, while scar formation was noted in the healed stage. Thrombi, marked intimal thickening, marked stenosis, and recanalization were seen in the coronary arteries. In KD without aneurysm, acute inflammation was localized in the intima and the perivascular area of the coronary arteries in the acute stages, but was absent in the healed stage. Although intimal thickening was noted, marked stenosis and thrombi were not evident in KD without aneurysm. In KD with and without aneurysm, acute angiitis in small arteries and micro-vessels and acute inflammation of various organs were noted in the acute stages, but disappeared in the healed stage. Fibrinoid necrosis of the artery was rare in the acute stages and was not noted in the healed stage. Atypical cases of KD showed the same pathological features as those in cases with clinically typical KD. The common cause of death in the healed stage was ischemic heart disease. Old myocardial infarction was noted in 80% of the cases, and acute myocardial infarction was seen in 35%. KD is an acute systemic inflammatory disease and KD without aneurysm is a disease with mild angiitis.

Autopsy↗
PubMedDate not supplied

Co-occurrence of alcohol, smokeless tobacco, cigarette, and illicit drug use by lower ranking military personnel.

The Worldwide Survey of Health Related Behaviors is administered periodically to a probability sample of military personnel. Earlier reports of these surveys suggested that illicit drug use was highest among the lowest ranking personnel. This paper reports a secondary analysis of the 1992 and 1995 surveys of the lowest ranking personnel. The results suggested that in general illicit drug users tended also to use alcohol, smokeless tobacco, and cigarettes. Heavy drinkers were more likely than light drinkers to use illicit drugs. No such relationship was observed between illicit drug use and the level of use of cigarettes or smokeless tobacco. Moreover, among the heavy drinkers, illicit drug users were especially likely to use cigarettes and among males, smokeless tobacco. The relevance of these results to military policies toward illicit drug use is discussed.

Adolescent↗
PubMedDate not supplied

Sympathetic block during spinal anesthesia in volunteers using lidocaine, tetracaine, and bupivacaine.

BACKGROUND AND OBJECTIVES: Spinal anesthesia to high thoracic dermatomes is alleged to result in almost complete block of all sympathetic efferent nerves. To examine the degree of sympathectomy during spinal anesthesia, the sympathetic response to a cold pressor test (CPT) applied to unblocked dermatomes before and during spinal anesthesia was measured with use of three different local anesthetics. METHODS: Twelve healthy volunteers were studied in a randomized and double-blind fashion on three separate occasions. In random order, each volunteer received approximately equipotent spinal doses of tetracaine 15 mg, bupivacaine 15 mg, and lidocaine 100 mg in hyperbaric solutions. Prior to and 30 minutes after spinal injection of local anesthetic, a CPT was applied for 2 minutes, and changes from baseline resting conditions in five physiologic variables were measured. RESULTS: The CPT 1 given before anesthetic administration resulted in an increase in heart rate, mean arterial pressure, cardiac index, and plasma concentrations of norepinephrine and epinephrine. Spinal anesthesia to a median level of T3 resulted in a decrease in mean arterial pressure by 10-12% but did not significantly decrease the other variables. Spinal anesthesia did not change the increase in heart rate or cardiac index in response to the second CPT, but the increase in mean arterial pressure was attenuated compared to the CPT before anesthesia. No increase in norepinephrine or epinephrine concentration was observed during the CPT given during spinal anesthesia. There was no significant relationship between level of analgesia and sympathetic response to stress. CONCLUSIONS: Spinal anesthesia with hyperbaric solutions of tetracaine 15 mg, bupivacaine 15 mg, and lidocaine 100 mg attenuated sympathetic function but did not produce complete sympathectomy. The effects were independent of the local anesthetic used.

Adult↗
PubMedDate not supplied

The relative increase in skin temperature after stellate ganglion block is predictive of a complete sympathectomy of the hand.

BACKGROUND AND OBJECTIVES: Although an increase in skin temperature of the hand implies sympathetic block after stellate ganglion block (SGB), it does not indicate complete sympathetic block unless accompanied by an absence of sweating because skin temperature may increase even with a partial sympathetic block. This study examined the efficacy of the SGB to block sweating in the hand and to determine if the magnitude of temperature change in the hand is predictive of a negative sweat test. METHODS: Fifty-nine SGBs were performed in 30 patients (15 women and 15 men) for diagnostic or therapeutic indications. Stellate ganglion block was performed via an anterior paratracheal approach at C6 using 15 mL 0.25% bupivacaine. Skin temperature was measured bilaterally on the index finger. A cobalt blue sweat test was performed bilaterally pre- and post-SGB on the middle finger. Successful sympathetic block after SGB was considered present when: (a) (change in ipsilateral temperature (postblock-preblock)] (Di)-[change in contralateral temperature] (Dc) > or = 1.5 degrees C; (b) Horner's syndrome present; and (c) sweat test changed from positive to negative. Logistical regression was applied to determine what value of Di - Dc could be used to predict a negative sweat test. RESULTS: Thirty-six percent (21/59) of blocks met all three criteria. Of the blocks where Di - Dc > or = 1.5 degrees C, 72% (21/29) had a negative sweat test post-SGB. Of the blocks where Di - Dc < 1.5 degrees C, 37% (11/30) had a negative sweat test postblock. If Di - Dc > or = 2.0 degrees C, a negative sweat test could be predicted with 69 +/- 12% sensitivity and 85 +/- 10% specificity. CONCLUSIONS: Stellate ganglion block often fails to increase skin temperature in the ipsilateral more than the contralateral hand. A value of Di - Dc > or = 2.0 degrees C was a good predictor of a sympathetic block, but was not sufficient to guarantee a complete sympathetic block of the hand after SGB in all cases. An apparently successful SGB as measured by "usual" clinical criteria may not result in a complete sympathectomy of the hand as is often assumed. Therefore, if obtaining a sympathectomy is important for diagnostic or therapeutic purposes, performing a sweat test provides important confirmatory evidence of the genuine success of the sympathetic block.

Adolescent↗