Biomedical subjects
Publications and source records attributed to J C Lin.
A case report of primary sternal osteomyelitis, a rare clinical entity, is presented. Treatment of primary sternal osteomyelitis is antibiotics and complete debridement of the infected bone and anterior periosteum. If the posterior sternal periosteum is not involved, it should be left intact. The defect can be covered with skeletal muscle flaps, which improves healing and minimizes recurrence. This approach led to a complete and timely cure.
We present serial magnetic resonance imaging (MRI) scans on a biopsy-verified case of Creutzfeldt-Jakob disease (CJD). The initial MRI scan demonstrated increased T2 signal-intensity within the basal ganglia and thalami. Subsequent MRI scans demonstrated a thin cortex, increased T2 signals diffusely within the white matter including U-fibers, and hypointense T2 signals within the basal ganglia, and thalami. Proton magnetic resonance spectroscopy (1H-MRS) study showed an absence of creatine, choline and N-acetylaspartate signals. By these characteristic findings, serial MRI and MRS studies may be helpful in differentiating CJD from other dementing illnesses.
In the present experiments, we measured N-methyl-D-aspartate (NMDA)-induced norepinephrine (NE) release and extracellular action potentials in the cerebellar cortex of urethane-anesthetized rats. The overflow of NE was measured using a Nafion coated-carbon fiber electrode and in vivo chronoamperometry. We found that both NMDA and quisqualate evoked NE release. Our previous work demonstrated that the electrophysiological activity of cerebellar Purkinje neurons could be either excited or inhibited by local NMDA application. It was reported that bicuculline antagonized NMDA-induced inhibition in Purkinje neurons, suggesting that a GABAergic mechanism was activated during NMDA application. We and others previously found that GABA-mediated electrophysiological depressions were enhanced by NE acting via beta-adrenergic receptors while these responses were decreased by activation of alpha-adrenergic receptors. Since NMDA evokes overflow of endogenous NE, the electrophysiological depression induced by NMDA may contain an NE-mediated modulatory component. In this study, we first examined the interaction of NMDA with beta-adrenergic agonist. We found that local application of isoproterenol facilitated NMDA- or GABA-mediated electrophysiological depressions of the Purkinje neurons. Applications of phenoxybenzamine, which antagonized the alpha-adrenergic response of synaptically released NE, also facilitated NMDA-elicited depression. In contrast, the depression induced by GABA, which did not induce NE overflow, was not potentiated by phenoxybenzamine. The facilitation of NMDA-induced depression by phenoxybenzamine was antagonized by the beta-adrenergic antagonist timolol. Taken together, these data suggested that the nonadrenergic pathway is involved in NMDA-induced electrophysiological responses in the cerebellum. NMDA may induce neuronal depression through modulation of GABAergic inhibition via NMDA-evoked NE release onto cerebellar Purkinje neurons.
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The two objectives of this study were to determine the range of recommended follow-up strategies for patients with lung cancer treated with curative intent and to estimate the cost of such follow-up. Ten articles delineating eight specific follow-up strategies were identified from a Medline search of the literature for 1980 through 1995. An economic analysis was done of the costs associated with the identified strategies. Charge data obtained from the Part B Medicare Annual Data file and the Hospital Outpatient Bill file were used as a proxy for cost. Follow-up intensity varied widely across strategies for 5 years of posttreatment follow-up. Medicare-allowed charges for 5-year follow-up ranged from a low of $946 to a high of $5645. When Medicare-allowed charges were converted to a proxy for actual charges by a conversion ratio of 1.62, the range was $1533 to $9145, a fivefold difference in charges. There was no indication that more intensive, higher-cost strategies increased survival or quality of life. The published literature, including textbooks, holds few answers in this area.
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Sarcoma of the hypopharynx has been reported very rarely in the literature, only six cases having been found among all head and neck malignancies reported to SEER (Surveillance, Epidemiology, and End Results) during 1973-1987. We report a 14-year-old boy with a huge malignant soft tissue sarcoma arising from the hypopharynx. Tracheostomy and feeding gastrostomy were performed as emergency life-saving procedures. Surgical resection had been attempted, but abandoned. Because of the rapidity of tumor growth, we gave the patient a course of accelerated radiotherapy (170 cGy/fraction, two fractions per day) with a total dose of 7140 cGy within one month. A series of endoscopy and imaging studies demonstrated complete regression of the tumor, and the patient is currently alive without evidence of disease 3.5 years after treatment. We conclude that for an unresectable tumor without distant metastasis, radiation therapy may be tried. The time, dose, and fractionation of radiotherapy should be carefully designed and individualized.
Distant metastasis has become the most frequent failure site-more so than locoregional relapse-after adequate radiotherapy in nasopharyngeal carcinoma (NPC). A prospective study was initiated to test the role of postradiation adjuvant chemotherapy using a weekly schedule for selected patients with high-risk NPC (N3, T4N2b-2c, and N2b-2c, with one of nodal size > 4 cm, or residual disease after radiotherapy). Through July 1993 to August 1994, a total of 20 patients were entered into the study: 16 men and four women, with a median age of 49 years and age range of 27-75 years. Pathology showed WHO type I:II:III = 2:13:5. Previous treatment consisted of concurrent chemoradiotherapy (16 patients), radiotherapy alone (two), and neoadjuvant chemotherapy followed by radiotherapy (two). Postradiation adjuvant chemotherapy was usually started 2 months after radiotherapy, using a weekly FP schedule (5-fluorouracil 1,250 mg/m2 + cisplatin 25 mg/m2, mixed in 100 ml saline, 24 h continuous i.v. infusion) for 18 weeks. The treatment of five patients was at 5, 6, 10, 14, and 15 weeks because of leukopenia-induced mortality, sudden death unrelated to adjuvant chemotherapy, a patient's refusal, and distant metastasis (the last two cases) during adjuvant chemotherapy. The major toxicity was leukopenia (grade I, 20%; grade II, 45%; grade III, 15%; and grade IV, 10%). Ten patients (50%) developed distant metastasis after a median follow-up time of 20 months. Our preliminary data indicate that postradiation adjuvant chemotherapy with a weekly FP regimen at our dosage is not recommended for high-risk NPC.
Kaposi's sarcoma (KS) is a multifocal vascular lesion characterized by abnormal proliferation of endothelial-like KS cells linked to a pronounced leukocyte infiltration. KS lesions contain novel herpes-like DNA sequences, KSHV, hypothesized to originate from the viral pathogen for KS. Using cultured KS cells that retain the KSHV sequences, diverse signals, including tumor necrosis factor alpha, interleukin (IL) 1 beta, polyinosinic acid/polycytidylic acid and lipopolysaccharide, induced the expression of the cytokine IL-6 and cellular adhesion molecules involved in leukocyte recruitment, including vascular adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1). The thiol-antioxidant pyrrolidine dithiocarbamate (PDTC) selectively inhibited > 90% of the activation of nuclear factor kappa B-like DNA binding activity in KS cells. PDTC also reduced by > 85% induced levels of VCAM-1 and IL-6 at the mRNA, protein, and functional levels in KS cells. In contrast, PDTC did not inhibit the induced expression of either ICAM-1 or E-selectin. These studies show that PDTC differentially modulates the expression of inflammatory response genes in KS cells that contain KSHV, suggesting that reduction-oxidation-sensitive events are involved in the regulation of these genes. These studies also suggest that thiol-antioxidants such as PDTC may play a potentially therapeutic role in the treatment of KS by preventing induction of specific inflammatory response genes that may be involved in the pathogenesis of KS.
A matched-dipole type catheter antenna is described for intracavitary and/or transluminal microwave treatment of diseases that may be responsive to thermal ablation therapy. This cap-choke antenna consists of an annular cap and coaxial choke design that can yield SAR distributions in and can produce heating of tissue surrounding the distal end of the catheter antenna. The cap-choke antenna is simple in construction, provides the desired specific absorption rate (SAR) distribution, and is efficient, i.e., the measured power reflection coefficient is 2% in tissue equivalent phantom modeling materials.
In the present study, we found that local application of serotonin (5-HT) potentiated ethanol-induced depressions of the spontaneous activity of Purkinje neurons in urethane-anesthetized rats. 5-HT also potentiated depressions induced by gamma-aminobutyric acid; however, this modulatory response was quantitatively smaller than 5-HT-induced potentiation of ethanol depression. Previous reports suggested that the release of 5-HT can be regulated by presynaptic 5-HT autoreceptors. We found that local application of methiothepin, which may induce 5-HT overflow through the inhibition of presynaptic autoreceptors, facilitated ethanol-mediated responses. This methiothepin effect was greatly diminished in neonatally 5,7-dihydroxytryptamine-lesioned animals, suggesting a presynaptic mechanism was involved. We also found that the 5-HT1A antagonist UH301 did not attenuate 5-HT-facilitated ethanol reactions. On the other hand, local application of 5-HT1B agonist CGS12066B potentiated ethanol-induced depression. Taken together, our data suggest that 5-HT can modulate ethanol-mediated electrophysiological depression, possibly mediated through 5-HT1B receptors in the cerebellum.
OBJECTIVE: To evaluate the relationship between acupuncture and cardiopulmonary function in healthy people. SUBJECTS AND METHODS: Healthy male volunteers were divided into 3 groups, 16 of persons each Group 1 was treated with acupuncture at points Neiguan (PC6) and Zusanli (ST36): Group 2 was treated with acupuncture at non-acupoints, and Group 3 was taken as control. The effects of resting cardiopulmonary functions were measured with gas analysis system. The resting heart rate (HR), oxygen consumption (VO2), and carbon dioxide production (VCO2) were recorded over a thirty-minute period at intervals of five minutes, 15 minutes, and 25 minutes. Electroacupuncture was given to Groups 1 and 2. The analysis of variance and t test were used in data analysis. RESULTS: In the acupuncture groups, resting heart rate and carbon dioxide production decreased (P < 0.05) and oxygen consumption also decreased slightly, although it was statistically insignificant (P > 0.05). CONCLUSION: Our results indicate that acupuncture can decrease the resting heart rate and carbon dioxide production, thus lowering the metabolic rate.
We explored a possible route of transmission of Kaposi's-sarcoma-associated herpes virus (KSHV) with nested and unnested PCR techniques. We looked for KSHV DNA sequences in semen of HIV-positive homosexual men and HIV-negative healthy semen donors. With unnested primers we found KSHV sequences in 21 of 33 (64%) homosexual men and in none of 30 healthy donors. With a nested PCR assay, 30 of 33 (91%) specimens from the homosexual men and 7 of 30 (23%) specimens from healthy donors had detectable KSHV sequences. Over 5 years of follow-up, 13 of 30 KSHV-positive homosexual men (43%) developed KS compared with none of the 3 KSHV-negative homosexual men.
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The purpose of this study is to investigate the hypothesis that ketamine, a non-competitive antagonist of the N-methyl-D-aspartate (NMDA) receptor, attenuates hypoxia-induced striatal dopamine release in vivo. High-speed chronoamperometric recording techniques, using Nafion-coated carbon fiber electrodes, were used to evaluate extracellular dopamine (DA) concentration in the striatum. KCl and DA were locally applied directly to the striatum of urethane-anesthetized Sprague-Dawley rats, in order to measure release and clearance, respectively, of DA. These anesthetized animals were paralyzed with D-tubocurarine and connected to a respirator to allow controlled respiration. Systemic concentrations of oxygen and carbon dioxide were altered by changing the partial pressure of O2, CO2, N2 of inspired air and the rate of the respirator. Our data indicate that lowering the respiratory rate from 90 to 20 times/min for 5 min, in room air, caused a decrease in blood O2 while increasing the CO2 concentration. These changes in blood gas concentration were reversible and reproducible. We also found that lowering the respiratory rates potentiated K(+)-induced DA release but not DA clearance in the striatum. In an attempt to induce hypercapnia, the room air was replaced with high CO2-containing air (15% CO2 + 20% O2 + 65% N2), and this change resulted in increased blood CO2 levels without lowering O2 concentration. The hypercapnia did not alter K(+)-induced DA release in the striatum. Next, we attempted to simulate anoxic hypoxia in the absence of hypercapnia. Respiration with pure N2 for 30 s resulted in lowering blood O2 without increasing CO2 levels. Both basal and K(+)-evoked DA releases were increased during N2-induced anoxic hypoxia. These data suggested that transient hypoxia facilitates DA release in the striatum. It has been suggested that NMDA is involved in many hypoxia-mediated responses. We also found that systemic application of ketamine, which itself did not affect blood O2 or CO2 levels, antagonized hypoxia-induced electrochemical responses. These data suggest that the increase in DA release in vivo during short-term hypoxia may probably be mediated through NMDA receptors.
OBJECTIVE: To assess the presence of different types of human papillomavirus (HPV) DNA in colorectal adenomas. DESIGN: The extracted DNA of 109 formalin-fixed, paraffin-embedded tissue sections of colorectal adenomas were analyzed by polymerase chain reaction and Southern blot hybridization. The correlations of HPV types 6, 11, 16, 18, and 33 DNA with the histological patterns of adenomas were also analyzed. RESULTS: Human papillomavirus DNA was detected in 28% of the adenomas. There were eight (21%) of 38 in tubular adenomas, 13 (33%) of 40 in tubulovillous adenomas, and 10 (32%) of 31 in villous adenomas. All HPV-6/11-positive cases were tubular or tubulovillous adenomas. However, most HPV-16 infections (8/12) were seen in villous adenomas. Human papillomavirus-positive adenomas included three (8%) of 38 that showed mild dysplasia, 10 (25%) of 40 that showed moderate dysplasia, and 18 (58%) of 31 that showed severe dysplasia. CONCLUSION: The association of the histological type with HPV-16 and the association of the grade of epithelial dysplasia with HPV DNA were highly significant. These associations support the adenoma-carcinoma hypothesis. In addition, the results suggest that HPV infection may be an important factor for the development of colorectal neoplasia.
The use of microwave energy for ablation of the atrioventricular (AV) junction was examined in open-chest dogs. Using a specially designed microwave catheter and a 2450 MHz generator, microwave energy was delivered to the AV junction according to one of two protocols. In protocol 1, increasing amounts of energy were delivered until irreversible AV block occurred. In protocol 2, only two applications of energy were used, one at low energy and the other at an energy found to be high enough to cause irreversible AV block. Each dog received between one and six applications of microwave energy. The amount of energy delivered per application ranged from 25.6 to 311.4 J. No AV block was seen at 59.4 +/- 28.3 J. Reversible AV block was seen with an energy of 120.6 +/- 58 J. Irreversible AV block was seen at 188.1 +/- 75.9 J. Irreversible AV block could be achieved in each animal. There was no difference in the energy required to cause irreversible AV block between the two protocols. The tissue temperature measured near the tip of the microwave catheter was correlated with both the amount of energy delivered and the extent of AV block caused. Histologic examination demonstrated coagulation necrosis of the conduction system. Microwave energy is a feasible alternative energy source for myocardial ablation. Since tissue damage is due exclusively to heating and the resulting rise in temperature can be measured, microwave energy may have advantages over currently existing energy sources in terms of both titrating delivered energy and monitoring the extent of tissue destruction.
Self-assembled monolayers of alkylsiloxanes supported on polydimethyl siloxane (PDMS) rubber were used as model systems to study the relation between blood compatibility and surface chemistry. The inner lumen of PDMS tubes was first treated with an oxygen plasma. The resultant oxidized surfaces were postderivatized by reacting them with alkyltrichlorosilanes to form the monolayer films. The chemical properties of the monolayers were controlled by varying the head-group chemical compositions. Surface derivatization was verified using variable-angle X-ray photoelectron spectroscopy (XPS or ESCA). Blood compatibility was evaluated using a canine ex vivo arteriovenous series shunt model. Surfaces grafted with hydrophobic head-groups as -CH3 and -CF3 had significantly lower platelet and fibrinogen deposition than the surfaces composed of hydrophilic groups such as -CO2CH3, -(CH2CH2O)3COCH3, and -(OCH2CH2)3OH.