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H P Hu

Publications and source records attributed to H P Hu.

10 recordsLinked to original sources
PubMed2001

Mechanism of anesthetic action: oxygen pathway perturbation hypothesis.

Although more than 150 years have passed since the discovery of general anesthetics, precisely how they work remains a mystery. We propose a novel unitary mechanism of general anesthesia verifiable by experiments. In the proposed mechanism, general anesthetics perturb oxygen pathways in both membranes and oxygen-utilizing proteins, such that the availability of oxygen to its sites of utilization is reduced, which in turn triggers cascading cellular responses through oxygen-sensing mechanisms, resulting in general anesthesia. Despite the general assumption that cell membranes are readily permeable to oxygen, existing publications indicate that these membranes are plausible oxygen-transport barriers. The present hypothesis provides a unified framework for explaining phenomena associated with general anesthesia and experimental results on the actions of general anesthetics. If verified by experiments, the proposed mechanism also has other significant medical and biological implications.

Anesthetics↗
PubMed1999

No effective prophylaxis of heterotopic ossification with short-term ibuprofen.

Ninety-five patients underwent primary total hip arthroplasty and routinely received ibuprofen for 5 days as prophylaxis for heterotopic ossification. This group was compared with a group of 99 patients who received indomethacin for 7 days as prophylaxis. After a follow-up of 1 year, the incidence of heterotopic ossification in the ibuprofen group was significantly higher than in the indomethacin group. The widespread ossification, Brooker grades III and IV, was prevented better by indomethacin than by ibuprofen. We conclude that ibuprofen for 5 days is not effective as prophylaxis for heterotopic ossification after primary total hip arthroplasty.

Adult↗
PubMed1993

The Geomedic knee prosthesis. A long-term follow-up study.

A retrospective long-term follow-up study of 189 Geomedic total knee arthroplasties in 143 patients was performed. One hundred and eighteen knees were replaced in patients with rheumatoid arthritis and seventy-one knees were replaced in patients with osteoarthritis. Fifty-seven knees were examined clinically with an average follow-up of 11 years. Seventy percent of these knees were painless. Lucent lines at the tibial bone-cement interface were observed in 62% of the follow-up radiographs (81 knees, mean follow-up: 10.5 years). Thirty-four prostheses (18%) were removed, with loosening of the tibial component as the main cause. Retropatellar pain was not a significant problem. The 13-year survival rate was 78%, with implant removal as an endpoint. Radiographically loosened components included, the 13-year survival rate was 58%.

Adult↗
PubMed1992

Signal intensity correlation of MRI with pathological findings in spinal neurinomas.

MR signal intensities at 0.282 T were correlated with the pathological findings in 23 cases of spinal neurinoma. With T2-weighted images (SE-T2WI or RARE-T2WI), all the tumors displayed high signal intensities similar to that of cerebrospinal fluid, indicating long T2 values. It is shown that the long T2 values of neurinomas are caused not only by intratumoral cystic formation, as reported by other authors, but also by intratumoral Antoni B structure, intratumoral micronecrosis and intratumoral vascular malformation. On SE-T1WI, the majority of neurinomas (73.9%) were isointense to spinal cord while the minority (26.1%) were hypointense. The similarity of the T1 values of neurinomas to that of the spinal cord may be related to the abundance of Schwann cells within the tumors, but tumors hypointense to cord and tumors isointense to cord on T1WI showed no significant difference in their gross and microscopic pathology.

Adolescent↗
PubMed1991

Contrast agents for magnetic resonance spectroscopy: a method to obtain increased information in in vivo and in vitro spectroscopy.

The concept of contrast, which now is an integral part of many magnetic resonance imaging studies, can be extended successfully to magnetic resonance spectroscopy. It involves the use of paramagnetic molecules whose distribution is restricted in some manner, thereby causing differential effects on the NMR spectra. As an illustrative example, the effects of lipophilic nitroxide stable free radicals on the NMR spectra of serum and lipoproteins are shown. These nitroxides differentially broaden away components of the spectra due to the nuclei of methylene and methyl groups, which enables the usually obscured peaks of lactate to be observed fully. The concept can be applied to differential distribution of the contrast agent on the basis of solubility, charge, and/or compartmentalization. It can be used with any type of NMR spectroscopy and any type of paramagnetic contrast (broadening) agent.

Animals↗
PubMed1991

Heterotopic ossification following total hip arthroplasty: a review.

Heterotopic ossification is the most frequent complication of total hip arthroplasty. When formed in the para-articular tissues, it may cause pain and restriction of hip motion. The present article extensively reviews the current literature on heterotopic ossification following total hip arthroplasty with regard to epidemiologic factors, clinical presentation and possible pathogenesis. Preventive measures are emphasized. Postoperative treatment with radiation and nonsteroidal antiinflammatory drugs have yielded good results in the prevention of heterotopic ossification. On the other hand, biophosphonates were ineffective. In comparison with radiation therapy, prophylaxis with nonsteroidal antiinflammatory drugs gave better results. Further research is still needed to define the most effective and safe medication regimen.

Aged↗
PubMed1991

The effect of biphosphonate on induced heterotopic bone.

HEBP (1-hydroxy, ethylidene-1, 1-biphosphonate) inhibited mineralization and was observed in matrix-induced heterotopic bone in rabbits. In one group of rabbits, HEBP was administered continuously until sacrifice 20 weeks after the operation. Another group of animals received HEBP for the first four weeks only. The effect of HEBP on de novo bone formation was determined by histologic and biochemical analyses. Implant alkaline and acid phosphatase levels and implant calcium and phosphate contents were measured. The implants of HEBP-treated animals showed diminished implant resorption and, at the same time, formation of atypical osteoid tissue. Quantitative measurements revealed a decrease of acid phosphatase activity, whereas implant alkaline phosphatase activity was unaffected. The mineralization, as depicted by the implant calcium and phosphate content, was almost completely inhibited during HEBP-administration. These effects were completely reversible after the withdrawal of the drug. Remineralization began directly after discontinuation, and recovered only 12 weeks later. The results of this study confirm reports that HEBP cannot prevent the formation of heterotopic ossification. The only effect would be a delay of mineralization during its administration.

Alkaline Phosphatase↗
PubMed1989

Development of nitroxides for selective localization inside cells.

The use of nitroxides to measure intracellular phenomena, especially oxygen concentrations, is a new and potentially important approach to a number of physiological and pathophysiological studies. This study provides data indicating the feasibility of developing nitroxides that localize selectively in the intracellular compartment; it is based on the use of readily hydrolysed ester linkages, such that the nitroxides become converted intracellularly to ionic derivatives that do not cross cell membranes readily. Up to 120-fold increased concentrations of intracellular nitroxides (and their one electron reduction product, the hydroxylamines) were obtained. The ESR spectra of the intracellular nitroxides were consistent with their conversion to the ionic species. Preliminary studies indicate that these nitroxides have the properties needed for their use as probes of intracellular concentrations of oxygen and that it should be feasible to synthesize nitroxides that will be even more effective for this purpose.

Animals↗
PubMed1989

Metabolism of aqueous soluble nitroxides in hepatocytes: effects of cell integrity, oxygen, and structure of nitroxides.

The optimum use of nitroxides in viable biological systems, including live animals, requires knowledge of the metabolism of nitroxides by major organ systems, especially the liver. We report here details of the metabolism of several prototypic aqueous soluble nitroxides in suspensions of freshly isolated hepatocytes. The general patterns of metabolism were similar to those observed in other types of cells (previous studies have been done principally in cells from tissue culture, such as CHO cells) including the primary initial reaction being reduction to the hydroxylamine, an increased rate of metabolism of some nitroxides in hypoxic cells, faster rates of reduction of nitroxides on six-membered piperidine rings compared to five-membered pyrrolidine rings, and most metabolism being intracellular. Metabolism in hepatocytes differed from other cell lines in having (1) significant reduction in the extracellular medium due to ascorbate that was released from damaged hepatocytes; (2) decreased rates of metabolism in freeze-thawed cells due to damage to subcellular organelles. These results provide much of the data needed to understand the role of the liver in the metabolism of nitroxides by intact animals and explain some previously puzzling results which indicated an apparent unusually high rate of metabolism of a charged nitroxide (Cat1) by hepatocytes. Our results also indicate that the use of freshly isolated cells or tissue homogenates may introduce experimental artifacts in the study of the metabolism of nitroxides.

Air↗