Intravenous Nicotine Simulation of Passive Smoking to Estimate Dosage to Exposed Non-Smokers

To estimate nicotine intake from passive smoking, six subjects received slow intravenous infusions of known doses of nicotine at a steady rate over one hour. The plasma and urinary nicotine concentrations produced by the infusions were compared with those found in previous studies of non-smokers exposed to tobacco smoke, in non-smokers in the general population, and in smokers during and after smoking their first cigarette of the day. It was estimated that the average rate of nicotine absorption was 0.23 mg/hr in a group of non-smokers exposed in a poorly ventilated public house, 0.36 mg/hr in non-smokers exposed to more extreme conditions in a smoke-filled unventilated room, and that the average daily-life exposure of a sample of 188 urban non-smokers was 0.014 mg nicotine per hour. In contrast, the dose absorbed by three smokers from their first cigarette of the day averaged 1.4 mg nicotine. The results indicate that when passive exposure of non-smokers results in carbon monoxide intake equivalent to the active smoking of one cigarette, the amount of nicotine absorbed is much less - equivalent to about one third of a cigarette dose. In view of the small samples and various assumptions in deriving these estimates, they can only be viewed as approximate.     

Maximum grip strength in normal subjects from 20 to 64 years of age.

The purposes of this study were to develop normative maximum grip strength (GRIP) data for men and women aged 20 to 64 years, separated into nine five-year age groups, and to develop prediction equations for GRIP using gender, age, height, weight, and hand dominance. A total of 1,182 volunteers (553 men and 629 women) participated in the study. Maximum hand grips were obtained using the Jamar dynamometer with standardized positioning and instructions. The hand to be tested first was chosen randomly. Each hand was then tested alternately. Three trials were performed on each hand. The highest GRIP for each hand was used for analysis. Two-way analyses of variance showed significant differences between the right and left hands and across the age groups for both genders. Follow-up analyses showed that significant decreases occurred between the age groups of 50-54 and 55-59 years in men and between the age groups of 50-54 and 60-64 years in women. The data also indicated that right and left GRIPs were highly correlated with each other (r = 0.93). Gender, height, and weight moderately correlated with both GRIPS (r = 0.52-0.73. Age correlated weakly with both GRIPs (r = -0.17). If either the right or the left GRIP was known, the other GRIP could be predicted easily from the known GRIP, with 87% of variance accounted for. Without the knowledge of the other GRIP, either GRIP could be predicted through gender, height, weight, age, and hand dominance, with 61% to 62% of the explained variance. The norms and prediction equations of GRIP developed in this study for men and women aged 20 to 64 years will help clinicians with decision making regarding grip strength.     

ADULT SPLENIC INJURIES: TREATMENT PATTERNS AND PREDICTIVE INDICATORS

Background : With the trend towards conservation in splenic trauma, the ability to identify a group of patients for whom we can safely offer conservative treatment becomes an important factor. Methods : Data were reviewed from the trauma register at the Auckland Hospital, Auckland, New Zealand, in an attempt to isolate any predictive factors that may allow more appropriate allocation of treatment modalities in the future. Methods of treatment were determined and the success or failure of conservative management noted. Differences in the demographics, Injury Severity Score (ISS) and computed tomographic (CT) findings were particularly sought. Results : Over a period of 111 weeks 48 patients were admitted with splenic injuries. Fifteen (31.2%) had immediate splenectomy, 27 (56.2%) were initially treated non-operatively and six (10.1%) died pre-operatively. Of the non-operative group eight (29.6%) failed this management at an average of 4.125 days into their hospital stay. No differences were found in age, mechanism, gender or ISS between the failed and successfully treated group. Using the Buntain classification of CT-graded splenic injury, 13 (87%) who had successful non-operative treatment had a grade II or III compared with six (86%) who failed this management being grade IV. Conclusion : Although these results did not reach statistical significance, by coupling the trends seen together with other work, CT grading of splenic injury is a predictive indicator and does appear to have a role in the early allocation of patients to appropriate treatment plans.     

Functional characterization of N-methyl-D-aspartic acid-gated channels in bone cells

Our recent identification of glutamate receptors in bone cells suggested a novel means of paracrine communication in the skeleton. To determine whether these receptors are functional, we investigated the effects of the excitatory amino acid, glutamate, and the pharmacological ligand, N-methyl-D-aspartic acid (NMDA), on glutamate-like receptors in the human osteoblastic cell lines MG63 and SaOS-2. Glutamate binds to osteoblasts, with a Kd of approximately 10(-4) mol/L and the NMDA receptor antagonist, D(L)-2-amino-5-phosphonovaleric acid (D-APV), inhibits binding. Using the patch-clamp technique, we measured whole-cell currents before and after addition of L-glutamate or NMDA and investigated the effects of the NMDA channel blockers, dizolcipine maleate (MK801), and Mg2+, and the competitive NMDA receptor antagonist, 3-((R)-2-carboxypiperazin-4-yl)-propyl-1-phosphoric acid (R-CPP), on agonist-induced currents. Both glutamate and NMDA induced significant increases in membrane currents. Application of Mg2+ (200 micromol/L) and MK801 (100 micromol/L) caused a significant decrease in inward currents elicited in response to agonist stimulation. The competitive NMDA receptor antagonist, R-CPP (100 micromol/L), also partially blocked the NMDA-induced currents in MG63 cells. This effect was reversed by addition of further NMDA (100 micromol/L). In Fura-2-loaded osteoblasts, glutamate induced elevation of intracellular free calcium, which was blocked by MK801. These results support the hypothesis that glutamate plays a role in bone cell signaling and suggest a possible role for glutamate agonists/antagonists in the treatment of bone diseases.     

The MRI appearance of the optic nerve sheath following fenestration for benign intracranial hypertension

Optic nerve fenestration is carried out in cases of severe benign intracranial hypertension. This study aimed to monitor the optic nerve sheath appearances and orbital changes that occur following this procedure. The eight patients were all female with an average age of 37.3 years and a range of 20–58 years. The duration of symptoms was 2–6 years. Symptoms included headaches, diplopia and visual obscurations. Examination revealed severe papilledema. All investigations, including MRI, biochemical and immunological tests, were negative. Patients had fenestration of a 2 mm × 3 mm segment of the medial aspect of the optic nerve sheath. Imaging was obtained with a 1 T MRI machine using a head coil. Coronal, axial and sagittal 3 mm contiguous sections using STIR sequences with TR 4900 ms, IT 150 ms and TE 60 ms were obtained. Five patients showed clinical improvement. The post-operative MRI findings in four of these included a decreased volume of cerebrospinal fluid (CSF) around the optic nerve sheaths and a localized collection of fluid within the orbit. There were no MRI changes in the three patients with no clinical improvement. Decreased CSF volume around the optic nerve and a fluid collection within the orbit may indicate a favorable outcome in optic nerve fenestration. Received 23 June 1997; Revision received 16 January 1998; Accepted 18 March 1998     

DNA analysis of skeletal tissue recovered from the English Channel

This case study reports on DNA analysis from different skeletal elements of an individual recovered 2 years after going missing in the English Channel. Selected bones were also re-submerged for an additional 2 years and re-analysed. By comparing results from both time points, this study concludes that high-load-bearing bones, particularly the bones of the feet, appear to be a preferable source of DNA for identification of skeletal tissue recovered from similar conditions.