Search PubMed⌕ Search

Biomedical subjects

A M Ho

Publications and source records attributed to A M Ho.

At least 37 records · Page 2Linked to original sources

Systemic air embolism after lung trauma.

Systemic air or gas embolism has been increasingly recognized as a complication of serious chest trauma and often presents with catastrophic circulatory and cerebral events. The classic findings are hemoptysis, sudden cardiac or cerebral dysfunction after initiation of PPV, air in retinal vessels, and air in arterial aspirations. The clinician must be wary of more subtle presentations. Several diagnostic tools (TEE, Doppler, CT) can detect intracardiac and cerebral air, but they may not be necessary to confirm the diagnosis of SAE. Cessation of SAE is essential for successful resuscitation. In those with unilateral lung injury, this can theoretically be achieved by isolating and ventilating the noninjured lung. Sole reliance on immediate thoracotomy for hilar clamping to stem the flow of gas emboli is a concept that needs to be challenged. Whether airway and ventilation interventions will eliminate, delay, or decrease the need for thoracotomy and improve the prognosis of SAE remains to be seen. There is little reported in the literature regarding such interventions. Airway management of a patient at risk for SAE should include a technique that can selectively ventilate each lung. Patients with bilateral sources of SAE may benefit from the avoidance of high airway pressures. Regional anesthesia should be considered when appropriate. HBOT is useful in managing cerebral air embolism and should be incorporated as soon as possible. Clinicians involved in trauma care must be familiar with SAE. By adopting a problem-based solution through innovative airway and ventilation management, anesthesiologists may significantly alter and improve the morbidity and mortality rate of SAE resulting from chest trauma.

Animals↗

Bronchial blocker placement through the lumen of an in situ tracheal tube.

Tracheal intubation during trauma resuscitation is almost always performed with a standard endotracheal tube. Difficulties may arise if lung isolation is required later. The options for achieving lung isolation in seriously traumatized patients are briefly reviewed. Two efficient and airtight systems to allow the insertion of a bronchial blocker with minimal risks are presented.

Adult↗

Capillary electrophoretic study of individual exocytotic events in single mast cells.

In this work we have demonstrated the application of on-column dynamic release of serotonin from individual granules within rat peritoneal mast cells (RPMCs). These granules are approximately 0.25 fl in volume and represent some of the smallest entities studied by capillary electrophoresis (CE). With the coupling of high-speed CE and laser-induced native fluorescence, a time resolution of 0.002 min and a detection limit of 0.9 amol (S/N = 3, rms) were achieved. By using a secretagogue as the running buffer for CE, we resolved the peak profile of individual degranulation events released due to exocytosis. The average amount of serotonin released for five RPMCs analyzed was 33 amol +/- 16%.

Animals↗

What to do when an endotracheal tube cuff leaks.

The authors describe an approach and a novel technique to solve a leaky endotracheal tube cuff problem in ventilator-dependent patients without immediately resorting to the potentially hazardous task of changing an endotracheal tube.

Adult↗

Immunosuppressive drugs prevent a rapid dephosphorylation of transcription factor NFAT1 in stimulated immune cells.

The immunosuppressive drugs cyclosporin A and FK506 interfere with the inducible transcription of cytokine genes in T cells and in other immune cells, in part by preventing the activation of NF-AT (nuclear factor of activated T cells). We show that transcription factor NFAT1 in T cells is rapidly dephosphorylated on stimulation, that dephosphorylation occurs before translocation of NFAT1 into the cell nucleus, and that dephosphorylation increases the affinity of NFAT1 for its specific sites in DNA. Cyclosporin A prevents the dephosphorylation and the nuclear translocation of NFAT1 in T cells, B cells, macrophages, and mast cells, delineating at least one mechanism that contributes to the profound immunosuppressive effects of this compound.

Animals↗

Radiographic diagnosis of breast implant rupture: current status and comparison of techniques.

Rupture of a breast implant is a recognized complication of augmentation mammaplasty and reconstructive breast surgery. Due to concerns over the extravasation of silicone gel within adjacent tissue and distant body sites, considerable attention has been given to the radiographic detection of mammary implant rupture. A metaanalysis comparing the accuracy of various currently available imaging modalities was conducted and an algorithm suggested to guide clinicians in the detection of breast implant rupture. Advantages and limitations of mammography, xeromammography, ultrasonography, MRI, and CT are outlined as well as some of the most specific radiographic signs of each with illustrative examples from patients evaluated at our institution. Results of our retrospective analysis corroborated by a review of the most recent literature reveal that mammography supplemented with ultrasonography constitutes the most cost-effective initial study, followed by MRI if these are equivocal. MRI is the most sensitive and specific study to evaluate breast implant rupture.

Breast↗

Expression of the transcription factor NFATp in a neuronal cell line and in the murine nervous system.

The transcription factor NFATp, which has a central role in cytokine gene induction in T cells, was previously thought to be expressed only in T cells and other immune cells. Here we report that NFATp is also expressed in the rat PC12 pheochromocytoma cell line and in the murine nervous system. Antisera against T cell NFATp recognize proteins of similar apparent molecular weight in T cells, PC12 cells, and murine olfactory bulb. The immunoreactive proteins from PC12 cells and from olfactory bulb bind to an NFAT site of the murine interleukin-2 promoter with the same specificity as T cell NFATp. Immunohistochemical staining localizes NFATp to neurons, specifically to olfactory receptor neurons and to their terminals in the olfactory bulb. The presence of NFATp in the nervous system suggests that it has a role in the transcription of specific neuronal genes in response to increases in cytosolic calcium.

Adrenal Gland Neoplasms↗

In vitro and in vivo expression of opioid and sigma receptors in rat C6 glioma and mouse N18TG2 neuroblastoma cells.

Mouse N18TG2 neuroblastoma and rat C6 glioma cell lines were injected into male nude mice, and the tumors were passaged serially. At each generation, tumors were analyzed for delta opioid binding using [3H][D-Ala2,D-Leu5]enkephalin and for sigma 1 and sigma 2 binding with 1,3-[3H]di-o-tolylguanidine in the presence and absence of 1 microM pentazocine. Receptor density (Bmax) and affinity (KD) were estimated by homologous competition binding assays. Opioid and sigma Bmax values in the solid tumors were significantly lower than their original levels in vitro. KD values for opioid/sigma ligands were similar in vitro and in vivo. With successive passages in the murine host, delta opioid and sigma 1 binding of the neuroblastoma-derived solid tumors became undetectable. In contrast, sigma 2 receptor Bmax values were unchanged with successive passages of the neuroblastoma-derived tumors and doubled in the nude mouse-borne gliomas. When neuroblastoma-derived solid tumors that were devoid of delta opioid binding were returned to culture, opioid receptors appeared to be up-regulated as compared with their original in vitro levels. Serial passaging of these recultured cells in vivo again resulted in a rapid decline in opioid receptor content. The opioid data are consistent with our prior findings on opioid binding diminution in human brain tumors. The pattern of change for sigma binding was more complex, with the sigma 2 response in late passages of the glioma being reminiscent of the formerly observed increase in number of sigma sites in transformed human meninges, kidney, and colon tissue.

Animals↗

Isolation of the cyclosporin-sensitive T cell transcription factor NFATp.

Nuclear factor of activated T cells (NFAT) is a transcription factor that regulates expression of the cytokine interleukin-2 (IL-2) in activated T cells. The DNA-binding specificity of NFAT is conferred by NFATp, a phosphoprotein that is a target for the immunosuppressive compounds cyclosporin A and FK506. Here, the purification of NFATp from murine T cells and the isolation of a complementary DNA clone encoding NFATp are reported. A truncated form of NFATp, expressed as a recombinant protein in bacteria, binds specifically to the NFAT site of the murine IL-2 promoter and forms a transcriptionally active complex with recombinant protein fragment react with T cell NFATp. The molecular cloning of NFATp should allow detailed analysis of a T cell transcription factor that is central to initiation of the immune response.

Amino Acid Sequence↗