Factors affecting conjugative transfer of plasmid pWG613, determining gentamicin resistance, in Staphylococcus aureus

Factors that are known to influence plasmid transfer in bacterial populations were studied for the conjugative plasmid pWG613, which determined gentamicin resistance in Staphylococcus aureus. The transfer frequency was largely unaffected over a wide range of temperature (18-42 degrees C); pH also had little effect on the transfer frequency in the range 5.0-8.5. High cell density and log phase cultures were required for optimal plasmid transfer, as were donor:recipient ratios of 0.003-3.3.     

Horner syndrome

Horner syndrome is an uncommon but important clinical entity, representing interruption of the sympathetic pathway to the eye and face. Horner syndrome is almost always diagnosed clinically, though pharmacological testing can be used to confirm the diagnosis. Imaging modalities such as PET, CT and MRI are important components of work‐up for patients presenting with acquired Horner syndrome. Our patient’s presentation with Horner syndrome unmasked the causative superior sulcus squamous cell carcinoma and a coincidental lower lobe adenocarcinoma. Successful radical treatment of these cancers resulted in complete resolution of the syndrome and disease‐free survival at 18 months. We review the anatomy and pathophysiology underlying this and other causes of Horner syndrome.     

Convergence of occipital nerve and superior sagittal sinus input in the cervical spinal cord of the cat

Co-existence of facial and occipital pain may occur in occipital neuralgia, migraine and cluster headache; suggesting convergence of trigeminal and cervical afferents. Such convergence has been shown in humans and other animals, but the site and extent of this are uncertain. In anaesthetized adult cats, the superior sagittal sinus and occipital nerve were stimulated electrically, and extracellular recordings made in the dorsolateral area of the upper cervical cord using glass-coated tungsten electrodes. Of 49 units in 10 cats, 33 (67%) had input from the superior sagittal sinus and the occipital nerve. Thirteen (27%) had superior sagittal sinus input and 3 (6%) had occipital nerve input. Convergent receptive fields were identified mechanically in 7 units. These experiments in cats show convergent input from occipital nerve and superior sagittal sinus on dorsolateral area units in two-thirds of cases studied. This experimental site of trigeminocervical convergence may relate to referral of pain in occipital neuralgia and other headaches.     

Nonsteroidal anti-inflammatory drugs (NSAIDs) and the kidney

In patients with PG-dependent renal function, NSAID administration constantly reduces GFR and RBF in a dose-dependent fashion. In this situation, the risk of overt acute renal failure is high and should be taken into proper account. In contrast, the incidence of NSAID-related renal structural alterations appears to be very low, yet the absolute number of patients may be significant considering the wide use of such drugs. Concerning the antiproteinuric effect of NSAIDs, the unfavourable ratio risk/benefit does not seem to support their indication in proteinuric nephropathies. The development of PGHS-2 selective inhibitors is promising, and may open new therapeutical strategies in the treatment of the progression of renal disease.      

Aminophylline in the emergency department. Maximizing safety and efficacy

An experimental technique designed to predict theophylline doses needed to attain therapeutic theophylline concentrations in 43 emergency department (ED) patients was compared with a standard conventional regimen in 46 ED patients. The experimental protocol utilized a computer-assisted dosage prediction program that incorporated baseline theophylline concentration rapidly obtained using a bedside assay. The standard protocol used conventional loading and infusion rates, as well as an estimate of time of last theophylline dose based on patient history. Plasma theophylline concentrations, estimated 1 and 6 hours after commencement of aminophylline therapy in each regimen, were compared. The experimental protocol was equally rapid but much more accurate in achieving targeted theophylline concentrations. Experimental dosage prediction was associated with a higher proportion of theophylline concentrations in the therapeutic range at 1 (81 percent vs 26 percent; p less than 0.001) and 6 hours (91 percent vs 37 percent; p less than 0.001). There was a trend toward fewer toxic concentrations recorded at 1 (0 percent vs 7 percent; p = 0.27) and 6 hours (0 percent vs 10 percent; p = 0.08). This protocol, which was performed quickly and without difficulty by residents in a busy hospital ED, offers an opportunity to improve the efficacy and decrease the toxicity of theophylline use in asthma emergencies.     

Incidence of AIDS dementia in a two-year follow-up of AIDS and ARC patients on an initial phase II AZT placebo-controlled study: San Diego cohort.

In a prospective study to determine the incidence of clinical dementia in patients with AIDS and ARC, 29 men and 3 women, 19 with ARC and 13 with AIDS, were examined neurologically and neuropsychologically every 6 months for 2 years during a placebo-controlled zidovudine (AZT) licensing trial. Most received two MRI brain scans. Although no patient was clinically demented at baseline, 9 (28%) developed dementia during the 2 years. Progression to dementia was associated with neuropsychological deterioration and with worsening on MRI during a preceding 6-month period, but not with baseline treatment group assignment. The results suggest that patients at CDC Stage IV who do not receive antiretroviral treatment earlier in their illness may develop clinical dementia at an annual rate of about 14%.