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Mark Wallace

Publications and source records attributed to Mark Wallace.

13 recordsLinked to original sources
PubMed2006

Post-infectious irritable bowel syndrome.

Irritable bowel syndrome (IBS) affects 8% to 22% of the general population. Although patients describe an insidious onset of symptoms, including abdominal pain relieved with bowel movements, excessive intestinal gas, variable bowel habits, and abdominal bloating, a subgroup of individuals describe the onset of IBS symptoms following an episode of acute gastroenteritis, known as post-infectious IBS (PI-IBS). Several studies have demonstrated the development of IBS following infection. Risk factors for the development of PI-IBS are female sex and longer duration of initial illness. Although the underlying mechanism of PI-IBS is unclear, ongoing inflammation is clearly a factor in the pathogenesis. The underlying inflammatory process results in increased enterochromaffin cells, T-lymphocytes, intestinal permeability, colonic transit time, and a variety of immunologic abnormalities. PI-IBS patients tend to have a better prognosis than do those with idiopathic IBS, with resolution of symptoms within 5 to 6 years. Treatment is similar to that of idiopathic IBS.

Bacterial Infections↗
PubMed2006

Highly active antiretroviral therapy is associated with improved survival among patients with AIDS-related primary central nervous system non-Hodgkin's lymphoma.

Highly active retroviral therapy (HAART) has been in widespread use in the United States since 1996. We sought to determine how the use of HAART influenced survival among patients with acquired immunodeficiency syndrome (AIDS) and primary central nervous system (CNS) non-Hodgkin's lymphoma (NHL). We used the population-based San Diego and Orange County cancer registry to identify 94 patients with both AIDS and CNS NHL diagnosed 1994-1999, of whom 31 were diagnosed 1996-1999. We performed Kaplan-Meier analyses to compare survival between patients who received HAART at NHL diagnosis or thereafter versus untreated patients and Cox proportional hazard models for adjusted survival. Among the patients diagnosed with NHL in 1996-1999, seven (23%) were taking HAART at the time of NHL diagnosis. Median survival was eight months for those who received HAART at the time of lymphoma diagnosis or after, versus one month for untreated patients. HAART, radiation therapy, and better performance status were associated with improved survival. We conclude that HAART prolongs survival in AIDS-related CNS NHL.

Adult↗
PubMed2004

Varicella-zoster virus transfer to skin by T Cells and modulation of viral replication by epidermal cell interferon-alpha.

Primary infection with varicella-zoster virus (VZV) causes the characteristic syndrome of varicella, or chickenpox. Experiments in severe combined immunodeficiency mice with human skin grafts (SCIDhu mice) indicate that VZV infection of T cells can mediate transfer of infectious virus to skin. VZV-infected T cells reached epithelial sites of replication within 24 h after entering the circulation. Memory CD4+ T cells were the predominant population recovered from skin in SCIDhu mice given uninfected or infected mononuclear cells, suggesting that immune surveillance by memory T cells may facilitate VZV transfer. The increased susceptibility of memory T cells to VZV infection may further enhance their role in VZV pathogenesis. During VZV skin infection, viral gene products down-regulated interferon-alpha to permit focal replication, whereas adjacent epidermal cells mounted a potent interferon-alpha response against cell-cell spread. Interleukin-1alpha, although activated in VZV-infected cells, did not trigger expression of endothelial adhesion molecules, thereby avoiding early recruitment of inflammatory cells. The prolonged varicella incubation period appears to represent the time required for VZV to overcome antiviral responses of epidermal cells and generate vesicles at the skin surface. Modulation of VZV replication by cutaneous innate immunity may avoid an incapacitating infection of the host that would limit opportunities for VZV transmission.

Animals↗
PubMed2004

Relative analgesic potency of fentanyl and sufentanil during intermediate-term infusions in patients after long-term opioid treatment for chronic pain.

Sufentanil, a potent mu-opioid agonist, historically has not been been given systemically to treat chronic pain. An implantable, fixed-rate osmotic pump that delivers sufentanil subcutaneously is being developed for this purpose. In that transdermal fentanyl may be a useful intermediary to estimate the appropriate sufentanil dose before implant, accurate information is needed about the relative analgesic potency of sufentanil and fentanyl during continuous infusion. To determine this relative potency, we administered these drugs to opioid-treated chronic pain patients using a target-controlled infusion (TCI). Sixty-three patients with stable chronic pain and daily oral opioid requirements equivalent to 100-1000 mg of morphine received TCI of fentanyl and sufentanil, each for a minimum of 16 h. Drug administration was double-blind and the order of administration was randomly assigned. Target concentration was changed until the patient reported that analgesia was adequate (defined as a pain level equal to or better than baseline). Seven patients did not complete the infusion and protocol violations invalidated data for 15 patients. For the remaining 41 patients, target concentrations associated with adequate analgesia were achieved for both sufentanil and fentanyl. The median value for the equianalgesic concentration ratio (steady-state fentanyl infusion to steady-state sufentanil infusion) was 7.5; mean potency ratio was 7.44 (95% confidence interval 6.8-8.2). During titrated, intermediate-term infusions in patients previously treated with opioids for chronic pain, sufentanil is approximately 7.5 times as potent as fentanyl.

Adult↗
PubMed2004

Intravenous lidocaine relieves severe pain: results of an inpatient hospice chart review.

BACKGROUND: Parenteral lidocaine has been reported to relieve neuropathic pain and/or pain refractory to opioid therapy. METHOD: A retrospective chart review of 768 consecutive patients acutely admitted to a hospice inpatient unit was performed to assess the efficacy and tolerability of parenteral lidocaine for pain relief. RESULTS: Eighty-two patients (approximately 11%) received parenteral lidocaine. Typically, a patient received a parenteral bolus and pain relief was evaluated 30 minutes later. If there was an effect, a continuous infusion was started. Sixty-one patients receiving lidocaine were evaluable for pain relief response. Fifty patients (82% of evaluable patients) reported a major response of their pain to lidocaine. Five patients (8% of evaluable patients) reported a partial response. Six (10% of evaluable patients) reported no benefit. DISCUSSION: Evaluable patients in an opioid refractory class had a 91% major response rate to lidocaine. Overall, lidocaine was well tolerated. Approximately 30% of evaluable patients reported some adverse event; the most common being lethargy. However, the effect was not clearly related to lidocaine. CONCLUSION: Parenteral lidocaine appears to be rapidly effective for opioid refractory pain and is well tolerated. A randomized controlled trial is needed to confirm these impressive but preliminary uncontrolled results.

Adult↗
PubMed2002

Coccidioidomycosis outbreak among United States Navy SEALs training in a Coccidioides immitis-endemic area--Coalinga, California.

An outbreak of coccidioidomycosis among 22 Navy SEALs occurred during training exercises in Coalinga, California. Ten (45%) of the 22 men had serologic evidence of acute coccidioidomycosis, the highest attack rate ever reported for a military unit. All case patients were symptomatic, and 50% had abnormal chest radiographs. There were no cases of dissemination and no deaths to date. Coccidioidomycosis continues to be a threat to military members and civilians who reside or train in areas where Coccidioides immitis, the causative agent, is endemic.

Adult↗
PubMed2002

Management of intrathecal catheter-tip inflammatory masses: a consensus statement.

OBJECTIVES: In a companion article, we synthesized current clinical and preclinical data to formulate hypotheses about the etiology of drug administration catheter-tip inflammatory masses. In this article, we communicate our recommendations for the detection, treatment, mitigation, and prevention of such masses. METHODS: We reviewed published and unpublished case reports and our own experiences to find methods to diagnose and treat catheter-tip inflammatory masses in a manner that minimized adverse neurological sequelae. We also formulated hypotheses about theoretical ways to mitigate, and possibly, prevent the formation of such masses. RESULTS: Human cases have occurred only in patients with chronic pain who received intrathecal opioid drugs, alone or mixed with other drugs, or in patients who received agents that were not labeled for long-term intrathecal use. Most patients had noncancer pain owing to their large representation among the population with implanted pumps. Such patients also had a longer life expectancy and exposure to intrathecal drugs, and they received higher daily doses than patients with cancer pain. Clues to diagnosis included the loss of analgesic drug effects accompanied by new, gradually progressive neurological symptoms and signs. When a mass was diagnosed before it filled the spinal canal or before it caused severe neurological symptoms, open surgery to remove the mass often was not required. Anecdotal reports and the authors' experiences suggest that cessation of drug administration through the affected catheter was followed by shrinkage or disappearance of the mass over a period of 2-5 months. CONCLUSIONS: Attentive follow-up and maintenance of an index of suspicion should permit timely diagnosis, minimally invasive treatment, and avoidance of neurological injury from catheter-tip inflammatory masses. Whenever it is feasible, positioning the catheter in the lumbar thecal sac and/or keeping the daily intrathecal opioid dose as low as possible for as long possible may mitigate the seriousness, and perhaps, reduce the incidence of such inflammatory masses.

Journal Article↗