Transluminal angioplasty of the vertebral and basilar artery

Transluminal angioplasty of brachiocephalic vessels for atherosclerotic lesions is now being performed in selected cases. We have thus far treated 17 cases of vertebral artery stenosis and one case of basilar artery stenosis by intravascular balloon dilatation techniques. Clinical presenting symptoms included vertebral basilar insufficiency, repeated transient ischemic attacks (TIAs), and multiple strokes. We performed successful transluminal angioplasty in 16 patients with marked narrowing (greater than 70%) of the dominant vertebral artery from atherosclerosis. One patient with basilar artery stenosis with tandem atherosclerotic lesions was also treated by angioplasty techniques. Repeat angiography at 3- to 12-month intervals has revealed continued patency at the angioplasty site. Complications occurred in our one patient with basilar artery angioplasty, who suffered a brainstem infarction after treatment, and in one patient who had a TIA after bilateral vertebral artery angioplasty. Two other patients had residual vertebral stenosis but remained asymptomatic after the procedure. All other patients who had successful dilatation were asymptomatic at 6 months to 2 years (mean, 15 months) of follow-up. These initial studies indicate that vertebral artery angioplasty may be effective for treating high-grade atherosclerotic lesions and for improving blood flow to the posterior circulation. Angioplasty of the basilar artery is technically more difficult and has a higher degree of risk because of the many perforating branches supplying the brainstem.     

Neurological manifestations of decompression illness in recreational divers - the Cozumel experience.

Neurological signs and symptoms are common in recreational divers with decompression illness (DCI). The spectrum of neurological manifestations, temporal profile, and laboratory findings are described in a large series of 200 consecutive recreational divers treated for DCI. The Hyperbaric Medicine Unit charts of 200 recreational divers treated for DCI were reviewed and analyzed. The cohort was mainly male, with a median age of 40 years, and quite experienced, with a median of 100 prior dives. In 44 divers (22%) a rapid ascent was documented. The median time to onset of neurological symptoms was 60 minutes after surfacing. One hundred seventy-seven of 200 divers (88.5%) had at least one symptom of neurological DCI at presentation. The most common neurological manifestations were paresthesia, dysesthesia, incoordination, motor weakness, and dizziness. Paresthesias were associated with significantly younger (p = 0.003) and less experienced (p = 0.03) divers. Similar but less significant correlations were noted for dysesthesias. Female divers were significantly more likely to experience painful skin symptoms (p < 0.001). Neurological manifestations are common in recreational divers treated for DCI. Neurological DCI and paresthesias are more likely to occur in younger and less experienced divers.     

Estimating shelf-life of drugs in solution

The use of pseudo-first-order chemical reaction kinetics and Arrhenius thermodynamic principles in estimating the effect of temperature on shelf-life of drug solutions is described. The degradation of many drugs in aqueous solutions occurs by hydrolysis. Equations using activation energy of the hydrolysis reaction (Ea) derived from Arrhenius principles, rate constants, and temperature are used to illustrate the exponential decrease in drug shelf-life proportional to an arithmetic increase in temperature. Use of the Q value, a factor based on Ea, rate constants, and temperature change, is described. The range of Ea for pharmaceutically important degradation reactions is relatively limited; thus, near room temperature, Q values of 2-5 can be used to estimate the effect of temperature change on shelf-lives of drugs in solution. To conservatively estimate effect on shelf-life when Ea is not known, a Q value of 2 is used to predict the increase in shelf-life obtained by decreasing storage temperature, and a Q of 5 is used to predict decrease in shelf-life from increasing the temperature. Sample calculations are used to show the application of equations based on these principles to practical temperature-dependent problems regarding shelf-life. Given information about shelf-life at a certain temperature, pharmacists can estimate safe shelf-life under other temperature conditions by using these equations.     

Prevalence of total hip replacement: how much demand has been met?

OBJECTIVE--To determine the prevalence of completed elective total hip replacements in a defined elderly population. DESIGN--Cross sectional postal questionnaire survey with additional data and validation from general practice and hospital records. SETTING--Six general practices in the English counties of Avon, Somerset, and Oxfordshire. SUBJECTS--A total of 7806 patients aged 65 years and over (94.7% response). RESULTS--The overall prevalence (95% confidence intervals) of elective total hip replacement was 5.3 (4.8,5.8)% Age and sex specific prevalences were 2.7 (2.0,3.5)% in men and 4.1 (3.3,4.9)% in women aged 65-74 years, and 5.2 (4.0,6.5)% in men and 8.8 (7.6,10.0)% in women aged 75 years and over. Of the 415 patients who had received elective total hip replacement, 28.2% had required bilateral surgery, 20% had received at least one operation privately, and 13% had required revision surgery. CONCLUSION--Our results show an increased level of satisfied demand for total hip replacement in elderly people compared with earlier estimates. The increasing prevalence of hip replacement is an indicator of increasing potential demand for revision procedures. Population based surveys are required to establish the level of unmet demand for primary procedures. Differences in past surgical activity may be important in interpreting the wide variation in current surgical rates.     

Suppressor-cell dysfunction in children with histiocytosis-X

Suppressor-cell activity of peripheral blood mononuclear cells were examined and lymphocyte subsets analyzed in children with histocytosis-X and in healthy, age-matched subjects. Suppressor-cell function was assessed by two methods, the indomethacin stimulation of mitogen-activated cultures and the concanavalin A-inducible suppressor-cell assay. The results of these two assays indicate that children with active disease have significantly decreased suppressor-cell activity. Additionally, the percentage and absolute number of OKT8⁺ lymphocytes were decreased in children with active disease. Suppressor-cell activity and lymphocyte subsets returned to normal, baseline levels with disease remission. This study documents for the first time suppressor-cell dysfunction and supports previous investigations in which suppressor T lymphocytes are deficient in children with active disease. These findings may explain certain clinical manifestations seen in children with histiocytosis-X.     

Lymphoma presenting as a salivary gland mass

A retrospective review of 36 cases of lymphoma presenting as a salivary gland mass was conducted over a 34-year period. A significant increase in the occurrence of lymphoma was noted in proportion to other salivary gland tumors (P less than 0.01, chi 2 analysis: 1954-1972, 11 of 714 (1.5%); 1973-1979, 9 of 201 (4.5%); 1980-1987, 16 of 265 (6.0%). The mean age was 61 years, sex distribution was equal, and 75% occurred in the parotid. Only 42% presented with signs or symptoms other than a painless mass. Glandular excision was done in early stages of the disease while biopsy was done at later stages. Frozen section analysis was accurate in all but one case and was useful in determining if biopsy were adequate. All patients were definitively treated with chemotherapy and/or radiotherapy. Several instructive points are apparent. Any patient presenting with an isolated salivary gland mass can have a lymphoma. There has, in fact, been a significantly increasing proportion of salivary gland lymphoma among the various salivary gland tumors in our patient population. In contrast to other salivary gland tumors, surgery is reserved for diagnosis and not for treatment. A lymph node biopsy may be sufficient to establish a diagnosis, in which case, glandular excision is unnecessary. Most of the patients presented with an asymptomatic isolated salivary gland mass. The presence of adjacent adenopathy, a rubbery feel to the mass, and the intraoperative appearance were the most suggestive signs of lymphoma. Frozen section analysis is helpful in determining the appropriate extent of surgery and is recommended.     

Undergraduate and postgraduate dental students''reflection on learning'': a qualitative study

The aim of this study was to explore undergraduate and postgraduate dental students' understanding of a good learning experience by using 'reflection on learning' as described by Schon. Four groups of Year 4 BDS students and one group of postgraduate students in dental public health took part in a series of focus group discussions. The responses were grouped into four broad themes (a) active, practical and positive learning; (b) interactive/together learning; (c) personal learning; (d) theory into practice. Six educational models of good learning proposed by the students are described.