The Effects of Breath-Holds and Muller Manoeuvres on Upper Airway Carbon Dioxide Concentration in Humans

<i>Background:</i> Obstructive sleep apnoea is caused by collapse of the upper airway. The presence of CO₂ in the upper airway lumen evokes a number of reflexes which favour upper airway re-opening, and we have proposed previously that CO₂ would build up in the upper airway following airway collapse and that this would contribute to reflex airway re-opening. However, it is not known if CO₂ can transfer from the alveoli to the anatomical dead space of the upper airway during apnoea. <i>Objectives:</i> To determine if alveolar CO₂ can enter the upper airway during breath-holds and Muller manoeuvres. <i>Material and Methods:</i> With local ethics committee approval, 6 male volunteers (aged 22–48 years), following a quiet inspiration, carried out breath-holds and Muller manoeuvres until breaking point. CO₂ was measured continuously in samples obtained from the hypopharynx using an infrared analyser with a sample rate of 50 ml/min. Muller manoeuvres (forced inspirations against a closed upper airway) mimic the respiratory efforts which occur during obstructive apnoeas. <i>Results:</i> In all cases, CO₂ increased progressively during apnoeas. There was a much larger increase in Muller manoeuvres (3.78 ± 0.51%, mean ± SEM at breaking point) compared to breath-holds. <i>Discussion:</i> These results show that upper airway CO₂ concentration rises substantially during apnoeas and suggest that transfer of CO₂ from the lungs to the upper airway may evoke a number of reflex effects which could affect breathing and upper airway re-opening during obstructive apnoeas.

Calcium silicate sorbent from secondary waste ash: heavy metals-removal from acidic solutions

The layer lattice, ion-exchange material, Al-substituted 11 A tobermorite, has been synthesised via an alkaline hydrothermal route from a secondary waste ash arising from newsprint recycling. The hydrogarnet, katoite (Ca3Al2SiO12H8), was also formed. Batch sorption analyses have confirmed that the Al-substituted 11 A tobermorite-bearing product is an effective sorbent for Co2+, Cd2+ and Zn2+ ions from acidified aqueous media. Kinetic sorption data were analysed in accordance with the pseudo-first- and pseudo-second-order models and steady state data were fitted to the Langmuir and Freundlich isotherms. The Langmuir and pseudo-second-order models provided the most appropriate descriptions of the sorption processes. The maximum uptake capacities for Co2+, Cd2+ and Zn2+ at 20 degrees C were found to be 10.47, 2.92 and 3.09 mg g(-1), respectively, and the respective apparent pseudo-second-order rate constants were estimated to be 5.08 x 10(-3), 1.10 x 10(-3) and 1.13 x 10(-3) g mg(-1) min(-1).

Low dose Vidaza and thalidomide is an effective combination for patients with myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML)

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Vidaza and thalidomide were administered to 29 patients with MDS or AML. Vidaza was given at a dose of 75mg/kg subq × 5 days q28 days and Thalidomide starting at 50mg/day and increasing to 100mg. Therapy was well tolerated. Median age was 70 years, and there were 16 males. Two patients had RA, 2 RARS, 9 RAEB, 4 CMMoL, 10 AML and 2 Unknowns. According to IPSS, 1 had low, 7 had Int-1, 5 had Int-2 and 4 had high risk disease, and 2 unclassified (10 had AML). Eleven patients had normal, 14 abnormal and 4 unknown for cytogenetics. Seven patients went off the study due to disease progression (5) or refused therapy (1), died within a week of treatment initiation (1) while 2 are on the first cycle and too early for evaluation. Twenty-five patients are evaluable for outcome. Ten patients received 5 or more cycles of Vidaza. HI was seen in 14/25 (56%), and stable disease in 6/25 (24%) while 5/25 (20%) had disease progression. Six patients experienced complete remission (CR) and are still receiving therapy (24%), 1 experienced HI-E, 2 HI-ANC, 3 HI-P, and 2 had a bilineage improvement (HI-P and ANC and HI-E and ANC). Of 10 AML patients, three went off study due to disease progression, 1 had stable disease, 6 responded with 4 complete remissions (CR), 1 HI-ANC and 1 HI-P. Interestingly, 6/10 AMLs had a history of prior MDS, 3/6 achieved CR, 2/6 had HI (ANC and platelets) and 1 has stable disease (continuing treatment). Among the 4 de novo AMLs, 1 had CR and 3 showed disease progression. We conclude that a combination of low dose Vidaza and thalidomide is well tolerated, and highly effective therapy for the treatment of patients with MDS as well as AML arising from a prior MDS. The ability to treat secondary MDS as out-patient and achieve such a high response rate represents a paradigm shift in AML therapy.

No significant financial relationships to disclose.

A humanized unconjugated antibody targeting CD33 (SGN-33; huM195) is active in patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS)

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Background: CD33 is a sialoglycan protein expressed on normal myeloid and monocytic cells as well as the vast majority of myeloid malignancies. A humanized antibody has been developed that recognizes CD33 and induces antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity. In prior clinical testing, this antibody led to significant reductions in blasts in patients with relapsed and refractory AML. Methods: A phase I single-arm dose escalation trial was initiated at multiple sites to assess the safety, immunogenicity, pharmacokinetics, and activity of SGN-33 at higher doses than previously tested. Cohorts of 3–6 patients with advanced MDS or AML will receive intravenous SGN-33 at weekly doses of 1.5 to 8 mg/kg over 5 weeks. Clinical response will be determined by bone marrow morphology and hematologic improvement. Responding patients will be eligible for 4 additional infusions. Results: Treatment of 6 patients at 1.5 mg/kg/wk has been well-tolerated, with no dose-limiting toxicity or related adverse events > grade 2. The median age is 79.5 years (range 52–88), and all patients were previously untreated. One patient discontinued treatment because of refractory thrombocytopenia, unrelated to SGN-33. CD33 saturation of the bone marrow blasts after 2 infusions ranged from 27% to 84% with an average of 55%. The mean change in bone marrow blasts by flow cytometry after 2 weeks was −9% (range −68% to +44%; N = 5), and the marrow monocytes changed by −39% (range −90% to +86%; N = 5). Two patients have completed re-staging after cycle 1. Blasts decreased from 29% to 12% in an 88 year-old woman with AML and from 11% to 9% in a 79 year-old man with RAEB. Conclusions: SGN-33 is well tolerated at 1.5 mg/kg/wk, and dose escalation is ongoing. Antitumor activity was seen in elderly patients with previously untreated AML and MDS. Incomplete saturation of the CD33 on bone marrow blasts suggests that higher doses may improve efficacy. SGN-33 holds promise for the treatment of patients with myeloid malignancy who are ineligible for aggressive therapy.

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Management of Brain Abscess and Lateral Sinus Thrombosis of Otogenic Origin: A Multidisciplinary Team Approach and Review of Literature

In this era of antibiotics the incidence of brain abscess and lateral sinus thrombosis (LST) secondary to chronic suppurative otitis media (CSOM) should not be underestimated and the management still remains a clinical challenge. We review the clinical records of patients who presented with temporal lobe abscess (Case 1), cerebellar and extradural abscess (Case 2) and LST (Case 3) of otogenic origin and discuss the importance of multidisciplinary team approach in the management of these high-risk cases. We review the literature in detail and discuss the epidemiology, clinical presentation, diagnostic modalities, treatment options and controversies in the management of brain abscess and LST.

Spinal Subpial Lipoma A Case Report and Review of the Literature

Spinal subpial lipoma is a rare entity and comprises only 0.9% of spinal cord tumours(l\ It arises from premature dysfunction of the cutaneous ectoderm during neural tube formation(2). We present a case of a 44-year-old male who presented with the symptoms attributed to this lesion, together with pathology, neuroimaging characteristics and management strategies

The effect of erythromycin on the pharmacokinetics of rosuvastatin

RATIONALE OBJECTIVE

To examine in vivo the effect of erythromycin on the pharmacokinetics of rosuvastatin [an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase]. Erythromycin is a potent inhibitor of CYP3A4 that markedly increases circulating levels of some other HMG-CoA reductase inhibitors.

METHODS

In this randomised, double-blind, two-way cross-over, placebo-controlled trial 14 healthy volunteers were given 500 mg erythromycin or placebo four times daily for 7 days. A single dose of 80 mg rosuvastatin was co-administered on day 4 of dosing. Plasma concentrations of rosuvastatin and active and total HMG-CoA reductase inhibitors were measured up to 96 h after dosing.

RESULTS

Eleven volunteers had data available from both dosing periods. There was no increase in rosuvastatin plasma exposure following co-administration with erythromycin compared to placebo. In fact, following co-administration with erythromycin, rosuvastatin geometric least square mean AUC((0-t)) and C(max) were 20% and 31%, respectively, lower than with placebo. Individual treatment ratios for AUC((0-t)) ranged from 0.48 to 1.17, and for C(max) ranged from 0.33 to 2.19. Essentially all of the circulating active HMG-CoA reductase inhibitors and most (>94%) of the total inhibitors were accounted for by rosuvastatin. Erythromycin did not affect the proportion of circulating active or total inhibitors accounted for by circulating rosuvastatin.

CONCLUSIONS

Erythromycin did not produce any increase in rosuvastatin plasma exposure. This indicates that CYP3A4 metabolism is not an important clearance mechanism for rosuvastatin, a result consistent with previous findings. The small decreases in rosuvastatin AUC((0-t)) and C(max) that occurred as a consequence of short-term treatment with erythromycin are unlikely to have relevance to long-term treatment with rosuvastatin.

The effects of the farnesyl transferase inhibitor FTI L-778,123 on normal, myelodysplastic, and myeloid leukemia bone marrow progenitor proliferation in vitro

The effects of the farnesyl transferase inhibitor FTI-778,123 on the proliferation of normal, MDS, AML, and CML hemopoietic progenitor cells was studied. MDS myeloid and erythroid progenitors are significantly more sensitive to FTI than normal progenitors while AML myeloid progenitors may be somewhat more sensitive than normal progenitors. In contrast, no difference between CML and normal progenitors are detectable. These data strongly suggest that a trial of this agent in patients with MDS and perhaps in patients with AML is indicated.

Erythrocyte CR1 expression level does not correlate with a HindIII restriction fragment length polymorphism in Africans; implications for studies on malaria susceptibility

Complement receptor 1 (CR1) expression level on erythrocytes is genetically determined, and in Caucasian populations is linked to high (H) and low (L) expression alleles identified by a HindIII restriction fragment length polymorphism (RFLP). Erythrocyte CR1 may be an important factor in determining malaria susceptibility, as low expression of CR1 reduces the rosetting of uninfected erythrocytes with Plasmodium falciparum-infected cells, a process that contributes to malaria pathogenesis. Prior to studying CR1 expression and malaria susceptibility, we have investigated whether the quantity of erythrocyte CR1 correlates with the H and L alleles in an African population. Mean erythrocyte CR1 in 149 Malian adults was 415 molecules per cell, which is comparable to Caucasian populations; however, there was no relationship between erythrocyte CR1 level and genotype for the HindIII RFLP (mean CR1 per erythrocyte HH = 414, HL = 419 and LL = 403, P > 0.1, Student's t-test). The conclusions of a previous study of erythrocyte CR1 expression level and malaria susceptibility in West Africa that was based on HindIII RFLP genotyping may therefore need to be re-evaluated.

Evolving concepts in myelodysplastic syndromes

Myelodysplastic syndromes continue to be "a riddle, wrapped in a mystery inside of an enigma". Clearly, MDS represent a heterogeneous group of disorders, and no uniform etiology or treatment can be prescribed for all patients. This further underscores the need for MDS patients to be seen at specialized centers and placed on experimental protocols if they need treatment. The important thing to remember is that ultimately, the patient must remain the measure of all things, and must be given all the therapeutic choices including that of waiting and watching with supportive care alone. Recent biologic insights have expanded the therapeutic options, but no curative therapies except stem cell transplants are available at this time. By dissecting the biology and focusing efforts towards understanding the etiology of the cytopenias, significant therapeutic advances are being made in this disease. The momentum built up so far must not be lost now.

A low-cost intervention for cleaner drinking water in Karachi, Pakistan

OBJECTIVE

To pilot test an inexpensive, home-based water decontamination and storage system in a low-income neighborhood of Karachi.

METHODS

Fifty households received a 20-L plastic water storage vessel with a high-quality spout and a regular supply of diluted hypochlorite solution. Twenty-five control households were recruited. Water samples were collected at baseline and during unannounced follow-up visits 1, 3, 6, and 10 weeks later.

RESULTS

Baseline drinking water samples among intervention households were contaminated with a mean 9397 colony-forming units (cfu)/100 mL of thermotolerant coliforms compared with a mean 10,990 cfu/100 mL from controls. After intervention the mean concentration of thermotolerant coliforms decreased by 99.8% among the intervention households compared with an 8% reduction among controls. Two years after vessel distribution, 34 (68%) of the families were still using the vessel. Thirteen of the households had stopped using their vessel because it had broken after more than 6 months of use, a pattern most consistent with ultraviolet radiation-induced degradation of the plastic.

CONCLUSIONS

In a highly contaminated environment, a specifically designed water storage container and in-home water chlorination was acceptable and markedly improved water quality. Where plastic water vessels will be exposed to substantial sunlight, ultraviolet light stabilizers should be incorporated into the plastic.

The clinical and biological effects of thalidomide in patients with myelodysplastic syndromes

Thirty patients with myelodysplastic syndromes (MDS) were treated with thalidomide at 100 mg/d p.o., increased as tolerated to 400 mg/d for 12 weeks. Levels of apoptosis, macrophage number, microvessel density (MVD), tumour necrosis factor alpha (TNF-alpha), transforming growth factor beta (TGF-beta), interleukin 6 (IL-6), vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were determined in the serum, bone marrow (BM) plasma and BM biopsies before and after therapy. Pretherapy biological characteristics of MDS patients were compared with similar studies performed in 11 normal volunteers. Ten patients demonstrated haematological improvement in the erythroid series, six becoming transfusion independent. Responders had a higher pretherapy platelet count (P < 0.048) and lower BM blasts (P < 0.013). Median time to response was 10 weeks, and four remain in remission beyond a year. Pretherapy MDS BMs showed higher MVD (P < 0.001) and TGF-beta (P < 0.03) and higher serum TNF-alpha (P < 0.008) compared with normal control subjects. After therapy, only BM TGF-beta decreased significantly (P < 0.002). Pretherapy haemoglobin was directly related to serum VEGF (P < 0.001) in responders and inversely related in non-responders (P < 0.05), suggesting the possibility that angiogenesis may be a primary pathology in the former and a consequence of anaemia-induced hypoxia in the latter. We conclude that thalidomide has important clinical and biological effects in at least a subset of MDS patients, but the precise mechanism of its action remains unknown and requires further study including a larger number of patients.

Utility of PCR in diagnosis of problematic cases of typhoid

Typhoid is a global problem. Conventional diagnostic methods have limitations. The Widal test gives a high proportion of false positive results, and indiscriminate use of antibiotics has reduced the utility of blood culture. Consequently, these procedures are inadequate for diagnosing suspected cases of typhoid that do not present clear-cut symptoms. We previously showed that PCR-based diagnosis of typhoid targeting the flagellin gene has unparalleled specificity. We assessed the utility of this method for diagnosis of problematic cases of typhoid. A comparative study of PCR, blood culture, and Widal test was carried out on 55 cases of suspected typhoid with fever for 3-30 days and possessing an ambiguous clinical picture. A control group comprised of 20 healthy persons was also included. The respective positive results by PCR, blood culture, and Widal test for these groups were 58.2 and 0%, 14.5 and 0%, and 52.7 and 45%. Sensitivity of PCR as compared with that of blood culture was significantly better. We concluded that PCR is much superior to conventional methods and, due to its high sensitivity and specificity, can be of great use for rapid and definitive diagnosis of problematic cases of typhoid.