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Biomedical subjects

S K Song

Publications and source records attributed to S K Song.

At least 55 records · Page 3Linked to original sources
PubMed1992

Concurrent quantification of tissue metabolism and blood flow via 2H/31P NMR in vivo. II. Validation of the deuterium NMR washout method for measuring organ perfusion.

The deuterium washout technique of measuring tissue blood flow is based upon NMR detection of HOD (administered as D2O saline, but typically detected as HOD because of rapid proton-deuteron exchange) as a freely diffusible tracer. Though this method is coming into more general use, it has not yet been rigorously validated in vivo against an accepted, independent measure of tissue blood flow. To this end, simultaneous radiolabeled microsphere and HOD washout blood flow measurements were made in rat gastrocnemius muscle. D2O saline was administered either intramuscularly or intraarterially (near the aortic bifurcation), and the sciatic nerve was electrically stimulated to increase the muscle blood flow rate. Over a range of flows of 2 to 80 ml/(100 g.min), comparison of microsphere and HOD washout measurements showed good agreement, with r = 0.92 (n = 16) for intramuscular administration and r = 0.91 (n = 12) for intraarterial administration. These data strongly suggest that the HOD washout technique provides accurate blood flow measurements in skeletal muscle.

Animals↗
PubMed1992

Concurrent quantification of tissue metabolism and blood flow via 2H/31P NMR in vivo. III. Alterations of muscle blood flow and metabolism during sepsis.

In the conclusion of this series of reports, the application of 31P/2H NMR to investigate the pathophysiology of sepsis in rat hindlimb muscle is demonstrated. Sepsis decreased muscle [PCr] by 18%, 18 +/- 4 SD vs 22 +/- 4 SD mmol/kg tissue wet wt (P = 0.01) in control rats but [ATP] was unchanged, 6 mmol/kg tissue wet wt (P = 0.2). The derived free cytosolic [ADP] in the two groups was similar, [ADP]septic = 0.023 +/- 0.004 SD and [ADP]control = 0.021 +/- 0.003 SD mmol/kg tissue wet wt, and not statistically different (P = 0.14). Likewise [Pi] in the septic and control groups was not statistically different, [Pi]septic = 1.1 +/- 0.5 SD and [Pi]control = 1.2 +/- 0.4 SD mmol/kg tissue wet wt (P = 0.2). Septic rats presented the symptom of respiratory alkalosis evidenced by elevated blood pH. Sepsis decreased muscle blood flow by 33%, P = 0.003, but examination of individual subjects did not demonstrate a correlation with the reduction in [PCr]. Thus, a metabolic energy deficit caused by cellular ischemia/hypoxia is not a likely cause of cellular abnormality in rat hindlimb muscle during sepsis.

Adenosine Diphosphate↗
PubMed1991

Effect of pretreatment on simultaneous saccharification and fermentation of hardwood into acetone/butanol.

The effectiveness of pretreatments on hardwood substrate was investigated in connection with its subsequent conversion by simultaneous saccharification and fermentation (SSF), using Clostridium acetobutylicum. The main objectives of the pretreatment were to achieve efficient separation of lignin from carbohydrates, and to obtain maximum sugar yield on enzymatic hydrolysis of pretreated wood. Two methods have given promising results: (1) supercritical CO2-SO2 treatment, and (2) monoethanolamine (MEA) treatment. The MEA pretreatment removed above 90% of hardwood lignin while retaining 83% of carbohydrates. With CO2-SO2 pretreatment, the degree of lignin separation was lower. Under the scheme of SSF, the pretreated hardwood was converted to acetone, butanol, and ethanol (ABE) via single stage processing by cellulase enzyme system and C. acetobutylicum cells. The product yield in the process was such that 15 g of ABE/100 g of dry aspen wood was produced. In the overall process of SSF, the enzymatic hydrolysis was found to be the rate-limiting step. The ability of C. acetobutylicum to metabolize various 6-carbon and 5-carbon sugars resulted in efficient utilization of all available sugars from hardwood.

Acetone↗
PubMed1991

Sepsis does not impair tricarboxylic acid cycle in the heart.

Sepsis has been reported to cause mitochondrial dysfunction and inhibition of key enzymes that regulate the tricarboxylic acid (TCA) cycle. We investigated the effect of sepsis on high-energy phosphates, glycolytic and TCA cycle intermediates, and specific amino acids that are involved in regulating the size of the TCA cycle pool during changes in metabolic state of the heart. Sepsis was induced in 12 female rats by the cecal ligation and perforation technique under halothane anesthesia; seven control rats underwent cecal manipulation without ligation. At 36-42 h postsurgery, the rats were reanesthetized, the chest was opened, and the hearts were freeze-clamped. Perchloric acid extracts of the hearts were analyzed with fluorometric enzymatic methods and 31P nuclear magnetic resonance spectroscopy. There were no significant differences in the levels of the TCA cycle intermediates or high-energy phosphates between the septic and control rats. The major metabolic changes were the 28% decrease in alanine and the 31% decrease in glutamate in the septic hearts compared with control (P less than 0.05 and P less than 0.005, respectively). Phosphocholine, a component of membrane phospholipids, was increased by 91% in the septic hearts (P less than 0.01). We conclude that sepsis does not impair the TCA cycle or induce significant cellular ischemia in the heart. The increase in phosphocholine may represent significant cellular membrane disruption during sepsis.

Adenosine Triphosphate↗
PubMed1991

Evaluation of the role of cellular hypoxia in sepsis by the hypoxic marker [18F]fluoromisonidazole.

Underlying cellular hypoxia, which may be difficult to detect, has been postulated to be a major cause of morbidity and mortality in sepsis. We employed the novel hypoxic marker [18F]fluoromisonidazole to determine whether cellular hypoxia was present in a peritonitis model of sepsis in the rat. A second group of septic and control rats had organ blood flow measurements determined by the radiolabeled microsphere technique to relate possible ischemia to decreased organ perfusion. No evidence of cellular hypoxia was detected in skeletal muscle, brain, liver, heart, or diaphragm in the septic rats. Ligation of the femoral artery caused a greater reduction in flow (55% decrease vs. 20% decrease, P less than 0.05) and an increased retention of [18F]fluoromisonidazole in skeletal muscle of the septic rats. We conclude that sepsis does not invariably result in systemic, i.e., multiorgan, cellular hypoxia and that underlying cellular hypoxia is not the major pathophysiological abnormality in sepsis. The greater reduction in muscle blood flow and the increased retention of [18F]fluoromisonidazole in the ischemic muscle of septic rats implies that they may be more vulnerable to hypoxia.

Animals↗
PubMed1990

Sepsis does not alter red blood cell glucose metabolism or Na+ concentration: a 2H-, 23Na-NMR study.

The effects of sepsis on intracellular Na+ concentration ([Na+]i) and glucose metabolism were examined in rat red blood cells (RBCs) by using 23Na- and 2H-nuclear magnetic resonance (NMR) spectroscopy. Sepsis was induced in 15 halothane-anesthetized female Sprague-Dawley rats by using the cecal ligation and perforation technique; 14 control rats underwent cecal manipulation without ligation. The animals were fasted for 36 h, but allowed free access to water. At 36 h postsurgery, RBCs were examined by 23Na-NMR by using dysprosium tripolyphosphate as a chemical shift reagent. Human RBCs from 17 critically ill nonseptic patients and from 7 patients who were diagnosed as septic were also examined for [Na+]i. Five rat RBC specimens had [Na+]i determined by both 23Na-NMR and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). For glucose metabolism studies, RBCs from septic and control rats were suspended in modified Krebs-Henseleit buffer containing [6,6-2H2]glucose and examined by 2H-NMR. No significant differences in [Na+]i or glucose utilization were found in RBCs from control or septic rats. There were no differences in [Na+]i in the two groups of patients. The [Na+]i determined by NMR spectroscopy agreed closely with measurements using ICP-AES and establish that 100% of the [Na+]i of the RBC is visible by NMR. Glucose measurements determined by 2H-NMR correlated closely (correlation coefficient = 0.93) with enzymatic analysis. These studies showed no evidence that sepsis disturbed RBC membrane function or metabolism.

Animals↗
PubMed1989

Meningeal nodules with features of extranodal sinus histiocytosis with massive lymphadenopathy.

We present an unusual case of multiple intracranial meningeal nodules in a 30-year-old man. Histologically, the nodules consisted predominantly of plasma cells, histiocytes, and lymphoid cells with Russell bodies and emperipolesis. Emperipolesis may be a clue to understanding the pathogenesis of the process that has features consistent with so-called sinus histiocytosis with massive lymphadenopathy in the extranodal location.

Adult↗
PubMed1985

Meningioma with intratumoral fat.

Fat within meningiomas is histologically not uncommon. Focal areas of low density on computed tomography scans within meningiomas have been demonstrated and are most often intratumoral cysts. The case presented demonstrates a focal area of low density within a meningioma that is proved histologically to be fat.

Female↗
PubMed1985

Contralateral hemiparesis following herpes zoster ophthalmicus.

A case of herpes zoster ophthalmicus was followed, after a latent period of four weeks, by contralateral hemiparesis. An attempt is made to clarify the anatomical relationships involved in the pathogenesis of postherpetic cerebral complications. Detailed presentation of neuropathological findings in this case may provide evidence of vasculitis in the syndrome, with better understanding of the pathological anatomy.

Aged↗
PubMed1984

Cholangiocarcinoma presenting as a cerebellar metastasis: case report and review of the literature.

Cholangiocarcinoma is an uncommon tumor that presents with hepatobiliary dysfunction. We report a patient with a chronic progressive organic mental syndrome, diffuse weakness, and gait disturbance who was discovered to have obstructive hydrocephalus due to a neoplasm. Pathologic examination revealed primary cholangiocarcinoma metastatic to the cerebellum. This tumor has not been previously reported to present with neurologic involvement.

Adenoma, Bile Duct↗
PubMed1983

Premonitory symptoms of stroke in evolution to the locked-in state.

Three patients, who subsequently developed the locked-in state characterised by quadriplegia and mutism with an alert sensorium, initially had mild dysarthria and uncrossed hemisensory or hemimotor deficits involving the face and ipsilateral extremities. Case one initially mimicked a left cerebral lesion with right hemisensory deficits, a mild right facial paresis and a right homonymous field deficit. Case two initially developed both left hemimotor and hemisensory deficits and later developed a paresis of right conjugate gaze. Case three presented with left hemimotor deficit, and mild paresis of conjugate gaze to the right. All three patients died. Rostral brainstem infarctions were found at necropsy in cases one and two. Case three had a radiolucent area of the brainstem demonstrated by CT Scan. Hemisensory and hemimotor deficits also have been noted to precede reported cases of pontine infarction with the locked-in state. Acute onset of uncrossed hemisensory and hemimotor deficits with dysarthria may be caused by infarction of the pons which may predispose to the locked-in state.

Aged↗
PubMed1972

Ethanol produces muscle damage in human volunteers.

Repeated administration of ethanol (42 percent of total calories) for 28 days increased serum creatine phosphokinase activity and produced ultrastructural changes in skeletal muscle of human volunteers. The data suggest that alcoholic myopathy results from ethanol toxicity, rather than from nutritional or other factors.

Adult↗
PubMed1971

Destruction of mammalian motor nerve terminals by black widow spider venom.

Black widow spider venom selectively poisons motor nerve endings. A progressive and irreversible failure of neuromuscular transmission occurs in the cat. Electron microscopy of the poisoned nerve-muscle junction shows a sequence of motor nerve ending damage that culminates in disruption of the prejunctional membrane and loss of all organelles, including synaptic vesicles. The postjunctional membrane was morphologically unaffected. After complete poisoning, the contractile response to exogenous acetylcholine was severely impaired, an indication that the prejunctional site is chiefly involved in the contractile response produced by exogenous acetylcholine and that the pre- and postjunctional effects of acetylcholine were separated.

Acetylcholine↗