Influences of morphine on the ventilatory response to isocapnic hypoxia

BACKGROUND: The ventilatory response to hypoxia is composed of the stimulatory activity from peripheral chemoreceptors and a depressant effect from within the central nervous system. Morphine induces respiratory depression by affecting the peripheral and central carbon dioxide chemoreflex loops. There are only few reports on its effect on the hypoxic response. Thus the authors assessed the effect of morphine on the isocapnic ventilatory response to hypoxia in eight cats anesthetized with alpha-chloralose-urethan and on the ventilatory carbon dioxide sensitivities of the central and peripheral chemoreflex loops. METHODS: The steady-state ventilatory responses to six levels of end-tidal oxygen tension (PO2) ranging from 375 to 45 mmHg were measured at constant end-tidal carbon dioxide tension (P[ET]CO2, 41 mmHg) before and after intravenous administration of morphine hydrochloride (0.15 mg/kg). Each oxygen response was fitted to an exponential function characterized by the hypoxic sensitivity and a shape parameter. The hypercapnic ventilatory responses, determined before and after administration of morphine hydrochloride, were separated into a slow central and a fast peripheral component characterized by a carbon dioxide sensitivity and a single offset B (apneic threshold). RESULTS: At constant P(ET)CO2, morphine decreased ventilation during hyperoxia from 1,260 +/- 140 ml/min to 530 +/- 110 ml/ min (P < 0.01). The hypoxic sensitivity and shape parameter did not differ from control. The ventilatory response to carbon dioxide was displaced to higher P(ET)CO2 levels, and the apneic threshold increased by 6 mmHg (P < 0.01). The central and peripheral carbon dioxide sensitivities decreased by about 30% (P < 0.01). Their ratio (peripheral carbon dioxide sensitivity:central carbon dioxide sensitivity) did not differ for the treatments (control = 0.165 +/- 0.105; morphine = 0.161 +/- 0.084). CONCLUSIONS: Morphine depresses ventilation at hyperoxia but does not depress the steady-state increase in ventilation due to hypoxia. The authors speculate that morphine reduces the central depressant effect of hypoxia and the peripheral carbon dioxide sensitivity at hyperoxia.     

Optic nerve decompression in fibrous dysplasia: indications, efficacy, and safety

Optic nerve decompression is controversial in posttraumatic visual loss and as a prophylactic therapy in fibrous dysplasia involving the optic canal. It is less controversial for the treatment of optic nerve compression in fibrous dysplasia. Thirteen patients with craniomaxillofacial fibrous dysplasia who underwent 16 optic nerve decompressions at the Chang Gung Craniofacial Centre for both therapeutic (10) and prophylactic (6) indications are reported. One patient sustained a clinically useful improvement in vision in response to two therapeutic decompressions, and another demonstrated marked improvement after therapeutic decompression, with visual acuity improving from 0.4 to 1.0 in the affected eye. No patient underwent a permanent deterioration of vision as a result of either therapeutic or prophylactic decompression. One patient suffered extraocular muscle dysfunction that was corrected with strabismus surgery. A review of the literature clarifies the controversies and allows establishment of indications for optic nerve decompression.     

Glypican 3 and glypican 4 are juxtaposed in Xq26.1

This paper reports the development of a dual column system for the simultaneous separation of fluorescent short-chain ceramide, 6-[(7-nitrobenz-2-oxa-1,3,-diazol-4-yl[NBD])amino]hexanoyl-sphingo sine and its metabolites, C6-NBD-sphingomyelin and C6-NBD-glucosylceramide, as well as the fluorescent derivatives of choline and serine phosphatides. The method enables the separation of these lipids in a single run on the basis of the polarity of their headgroups and hydrophobicity of their acyl backbone. The fluorescent properties of the NBD-label make it possible to quantitate small amounts of NBD-lipid analogues. The sensitivity of the presented method thus permits the use of small sample volumes and the determination of NBD-lipid analogues secreted into mouse bile directly, without prior extraction or concentration steps.     

Styrene toxicity: an ecotoxicological assessment

Although other aromatic compounds (e.g., benzene, toluene, polycyclic aromatic hydrocarbons (PAH), etc.) have been thoroughly studied over the years, styrene has been given little attention probably due to its lower rate of industrial use. In addition, it is less toxic than benzene and PAH, proven carcinogens. However, it is classified as a mutagen and thus potentially carcinogenic. Its main use is in the production of the polymer polystyrene and in the production of plastics, rubber, resins, and insulators. Entry into the environment is mainly through industrial and municipal discharges. In this review, the toxicological effects of styrene on humans, animals, and plants are discussed. Its mode of entry and methods of monitoring its presence are examined. Although its effects on humans and aquatic life have been studied, the data on short- or long-term exposures to plants, birds, and land animals are insufficient to be conclusive. Since exposure to workers can result in memory loss, difficulties in concentration and learning, brain and liver damage, and cancer, development of accurate methods to monitor its exposure is essential. In addition, the review outlines the present state of styrene in the environment and suggests ways to deal with its presence. It might appear that the quantities are not sufficient to harm humans, but more data are necessary to evaluate its effect, especially on workers who are regularly exposed to it.     

Effect of nickel chloride on mouse T-lymphocyte subsets

The usual features of non-Hodgkin lymphomas (NHL) of the mucosa-associated lymphoid tissue (MALT) include monocytoid B-cell proliferation, and chronic inflammatory precursor lesions. Despite a reputation of being indolent, NHL of the MALT may disseminate to other MALT areas, and raise difficult therapeutic questions. We report a case of gastric NHL of the MALT whose evolution, despite an initial surgical treatment considered radical, was noticeable for a well documented breast relapse.     

Tryptophan in bovine rhodopsin: its content, spectral properties and environment

The tryptophan content of purified bovine rhodopsin was obtained by two independent methods: direct analysis of hydrolysates prepared by digestion of opsin with methanesulfonic acid containing 0.2% 3-(2-aminoethyl)indole and a computer-assisted analysis of the near-UV spectrum of rhodopsin. Both methods gave a value of eight tryptophan residues per rhodopsin. Based on the near-UV spectral analysis, the light-induced difference spectrum of rhodopsin, and the susceptibility of residues to oxidation by N-bromosuccinimide, we concluded that approximately half of the tyrosine and tryptophan residues are shielded to some extent from the aqueous solvent, that two of the tryptophan residues are in very apolar environments, and that following light excitation at least one of these tryptophan residues and several tyrosines are exposed to an aqueous environment. Analysis of rhodopsin absorption in the far-UV indicated that below 240 nm, approximately half of the absorption is due to aromatic residues and that the other half is largely due to the peptide bond. The effect of illumination on secondary structure is to induce a loss in helical structure, calculated to involve 35% of the amino acid residues in purified rhodopsin. If light-induced changes in secondary structure are specifically excluded, most of these results can be extended to bovine rod outer segment membranes.     

Modern medical electricity in the management of pain

With the economics of medical care and the history of electrotherapeutics firmly in mind, one should seek treatments that are efficient and effective. There is no question that relief of the symptom of pain must be a primary focus of treatment, whether or not a specific pathology is known. Electric devices may be justifiably used for their placebo effects, if the cost is reasonable, because side effects are minor and infrequent. Research shows specific neurochemical effects of several electrotherapeutic devices, supporting the notion that specific therapeutic effects exist in addition to placebo effects. Passage of time and further research will determine which of the current techniques and devices will find their way into future similar articles or monographs.     

Factors influencing functional outcome in supraglottic laryngectomy

BACKGROUND: The relationship between preoperative pulmonary function tests (PFTs) and postoperative aspiration and deglutition complications in supraglottic laryngectomy (SL) has not been adequately analyzed. The effects of numerous other variables are either controversial or have not been studied. METHODS: A retrospective chart review was performed on 46 SL patients, analyzing preoperative PFTs and arterial blood gases, demographic factors, stage of disease, extended resections, cricopharyngeal myotomy, hyoid preservation, neck dissection, and postoperative radiotherapy with regards to aspiration and deglutition problems. RESULTS: Eighteen (39%) patients had no problems, 15 (33%) had moderate problems, and 13 (28%) had severe problems; of these, 39 (85%) were ultimately successful with no further swallowing dysfunction, whereas seven (15%) suffered intractable aspiration difficulties. Decreasing FEV1/FVC was significantly correlated with a poorer outcome, as was a greater number of pack-years of smoking. The effect of FEV1/FVC was shown to be independent from pack-years, whereas the converse was not clearly demonstrated. Extensions of the standard procedure did not correlate significantly with increased problems. CONCLUSIONS: An FEV1/FVC less than 50% signifies a greater risk for severe aspiration and deglutition complications, although it must be regarded as one factor among many in determining operability. With careful attention to reconstruction, extensions of the standard SL procedure can be safely performed.     

On the roles of urocanic acid in photoimmunosuppression: attempted photorepair of urocanic acid-DNA cyclobutane adducts with DNA photolyase

It has been reported that UV-induced immunosuppression can be reversed by photoreactivation or exposure to T4 endonuclease V, two treatments that can repair cyclobutane pyrimidine dimers. These observations, together with the known role of urocanic acid (UA) in UV-induced immune suppression, prompted us to study the ability of DNA photolyase to repair UA-DNA cyclobutane photoadducts in single-stranded calf thymus DNA. We did not detect any release of UA, with a sensitivity implying that photolyase is at least 2900 times less active toward UA-DNA adducts than toward cis-syn thymine-thymine dimers. This indicates that any reversal of photoimmunosuppression by photoreactivation cannot significantly involve cleavage of UA-DNA cyclobutane adducts.     

Myocardial perfusion and function in dogs with moderate coronary stenosis

MRI studies of first-pass contrast enhancement with polylysine-Gd-DTPA and myocardial tagging using spatial modulation of magnetization (SPAMM) were performed to assess the feasibility of a combined regional myocardial blood flow and 2D deformation exam. Instrumented closed-chest dogs were imaged at a baseline control state (Cntl) followed by two interventions: moderate coronary stenosis (St) achieved by partial occlusion of the left anterior descending (LAD) and moderate coronary stenosis with dobutamine loading (StD). Hypoperfusion of the anterior region (ANT) of the myocardium (LAD distribution) relative to the posterior wall (POS) based on the upslope of the signal intensity time curve from the contrast-enhanced MR images was demonstrated only with dobutamine loading (ANT:POS Cntl = 1.077 +/- 0.15 versus ANT:POS StD = 0.477 +/- 0.11, P < 0.03) and was confirmed with radiolabeled microspheres measurements (ANT:POS Cntl = 1.18 +/- 0.2 ml/min/g versus ANT:POS StD = 0.44 +/- 0.1 ml/min/g; P < 0.002). Significant changes in regional myocardial shortening were only seen in the StD state (P < 0.02); the anterior region showed impaired myocardial shortening with dobutamine loading (P = NS), whereas the nonaffected POS region showed a marked increase in shortening when compared with Cntl (Cntl = 0.964 +/- 0.02 versus StD = 0.884 +/- 0.03; P < 0.001). These results demonstrate that an integrated quantitative assessment of regional myocardial function and semiquantitative assessment of myocardial blood flow can be performed noninvasively with ultrafast MRI.