Structure-pulmonary toxicity/retention relationships of inhaled fluorocyclobutenes

Hexafluorocyclobutene (HFCB) and derivatives have been used as fumigants, refrigerants and polymerization monomers. When inhaled they produce a potentially fatal pulmonary oedema similar to that induced by perfluoroisobutene (PFIB), a by-product of Teflon manufacture. This study determined the relationship between the chemical structure, respiratory retention and toxicity of HFCB and five analogues in rats and mice. Retention in the rat was determined using a flow-through system combining nose-only exposure and plethysmography. Structural changes to HFCB modified retention. At concentrations of ca. 1 ppm, where uptake was independent of exposure time, the rate of uptake was increased by halogen substitution in the order 3-Br = 1-Br = 1-Cl > 3-Cl = 1-H > HFCB, and was a function of volatility. At concentrations of 6 or 30 ppm, the percentage retained and rate of uptake decreased with time. The total mass retained (micromol kg(-1)) was not proportional to inhaled concentration and was best described by the calculated partition coefficient (octane-water). No clear relationship between retention and reactivity was apparent. The contribution of volatility, partition coefficient and reactivity to the uptake process depended on inhaled concentration. The toxicity of the fluorocyclobutenes agreed with reactivity relationships based on electrophilicity (lowest unoccupied molecular orbital energy), carbanion stability and leaving-group mobility. Toxicity is based principally on the number of successive alkylations (1, 2 or 3) that can occur with tissue nucleophiles.     

Case report. The iron rim sign.

A chronic cystic cerebral hematoma occurred in the frontal lobe and mimicked both clinically and radiographically a frontal sinus mucocele. A rim seen on multidirectional tomography and unenhanced computed tomography was presumed to be composed to calcium. However, electron microscopic analysis revealed the rim to be composed almost entirely of iron from hemosiderin breakdown products. This is the first such report of an "iron rim" that we could find in the literature.     

Inability to demonstrate hydroxylation of tyrosine by murine melanoma "tyrosinase" (L-DOPA oxidase), using the tritiated water assay technique.

Validity of the tritiated water assay technique for tyrosine hydroxylase activity as a qualitative method was demonstrated with mushroom tyrosinase. Using this method, isolated murine melanoma "tyrosinase" (L-dopa oxidase) showed no tyrosine hydroxylase activity. This finding supports previous studies in our laboratory which used a variety of histochemical and biochemical methods. The nonenzymatic production of tritiated water caused by tritium exchange with hydrogen peroxide complicates the use of the tritiated water assay technique with crude systems, since hydrogen peroxide is generated by a variety of oxidase reactions. For this reason, previous studies using the tritiated water assay technique with crude systems are ambiguous.     

Postnatal depression and infant growth and development in low income countries: a cohort study from Goa, India.

BACKGROUND: Postnatal depression is a recognised cause of delayed cognitive development in infants in developed countries. Being underweight is common in South Asia. AIMS: To determine whether postnatal depression contributes to poor growth and development outcomes in Goa, India. METHODS: Cohort study for growth outcomes with nested case-control study for developmental outcomes. A total of 171 babies were weighed and measured at 6-8 weeks following birth. The following measures were used: Edinburgh Postnatal Depression Scale for maternal mood, and sociodemographic and infant health variables. Outcome measures were: weight (<5th centile), length (<5th centile), and Developmental Assessment Scale for Indian Infants scores at six months. RESULTS: Postnatal depression was a strong, and independent, predictor of low weight and length and was significantly associated with adverse mental development quotient scores. CONCLUSIONS: This study provides evidence for the first time that postnatal depression, a potentially treatable disorder, is a cause of poor growth and development in South Asia.     

Superior mesenteric artery bypass for chronic mesenteric ischaemia: a DGH experience

This article evaluates the results of single vessel bypass surgery for symptomatic chronic mesenteric ischaemia (CMI) in 6 patients undergoing a total of 8 superior mesenteric artery (SMA) bypass operations, all with good post-operative symptom relief. Post-prandial pain and weight loss was present in 5 out of 6 patients. Epigastric bruit was present in only two patients and 4 out of 6 patients had diarrhoea. The patients had varying degrees of peripheral vascular disease, ischaemic heart disease and hypertension. All patients had occlusion of the SMA on angiography and bypassing the occluded segment resulted in disappearance of the symptoms and weight gain. The vascular graft was sutured end to side to the front of the infra-renal aorta and end to side to the SMA, distal to the origin of the middle colic artery. Two patients had recurrence of symptoms due to graft occlusion at 3 and 4 years, respectively; they were successfully treated with repeat SMA bypass. There were no major complications or deaths related to the procedure in this study; one patient developed an incisional hernia requiring elective repair. Thus, early restoration of SMA circulation by bypass grafting in patients with CMI is sufficient to alleviate symptoms and prevent intestinal infarction with its high mortality rate.     

Laparoscopic nephroureterectomy. A new standard for the surgical management of upper tract transitional cell cancer

Laparoscopic nephroureterectomy for upper tract TCC still remains somewhat controversial. Unlike laparoscopic radical nephrectomy, which has become widely accepted, LNU is still in its earliest stages. Although there are obvious benefits for the patient who has LNU--less pulmonary complications, less postoperative discomfort, a shorter hospital stay, a better cosmetic result, and a brief convalescence--there are significant concerns. The longer operative time creates a negative financial and professional inducement to learn this technique. Operative times need to fall into the 4-hour range or less to make the procedure cost-effective. Analysis of the efficacy of laparoscopic nephroureterectomy as a curative treatment modality is important. In the short-run, LNU seems to provide similar results to open nephroureterectomy for upper TCC. Although concerns over port site seeding, bladder recurrence, and intraperitoneal seeding have been voiced, these problems have not occurred. The higher incidence of local recurrence noted in the authors' series, however, is of concern and remains an unsettled issue. Despite these local recurrences, the overall cancer survival for a given grade and stage of upper tract TCC seem to be similar to survivals recorded after open nephroureterectomy. Still, the number of LNU cases remains small, and follow-up is brief. These patients need to be monitored closely, with follow-up CT scans over the next decade. The authors believe that there are still several significant hurdles standing in the path of LNU before it can become a widely accepted procedure. Issues of cost, training, and long-term efficacy must be answered definitively. To obtain these types of data, it will be necessary to create a multi-institutional, cooperative study to obtain sufficient numbers of patients with a more than 5-year follow-up on which to base future recommendations.     

Calcaneal bone mineral density and mechanical strength of the metatarsals

The primary aim of this study was to determine the predictive value of the bone mineral density of the calcaneus for fracture of the metatarsals. The authors report a strong positive correlation between the bone mineral density of the calcaneus and the four-point bending strength of each of the five metatarsals (r2 = 0.76, 0.64, 0.70, 0.68, and 0.78 for metatarsals 1 through 5, respectively). In addition, the relative strengths of the metatarsals and the correlation with their in vivo loads during gait as previously reported in the literature are discussed.     

A comparative study of subsyde-CR versus meloxicam in rheumatic disorders

A prospective, randomised comparative clinical study was conducted in adult patients of either sex presenting with articular and non-articular rheumatic conditions commonly encountered in clinical practice Rheumatoid arthritis, osteo-arthritis, cervical spondylosis, and lumbago/sciatica were the most frequent conditions encountered in both the groups, followed by others like tenosynovitis, frozen shoulder, prolapsed disc, fibrositis, myositis, sprains, strains and so on. The drugs that were employed for therapy were diclofenac in a controlled release formulation employing the DRCM technology (subsyde-CR) and meloxicam in a standard formulation marketed in our country. Both drugs were well tolerated and found to be effective in reducing the signs and symptoms of the disease entities throughout the study period, but subsyde-CR was observed to produce a somewhat greater reduction in signs and symptoms scores that meloxicam, a difference that could be possibly attributed to the greater efficacy of subsyde-CR in non-articular rheumatic conditions. On the basis of the available literature on diclofenac and meloxicam as well as the DRCM technology in formulating subsyde-CR, it is reasonable to conclude that a controlled release formulation of diclofenac based on the DRCM technology offers a safe and effective alternative to other non-steroidal anti-inflammatory drugs such as meloxicam.