Use of inferior vena cava filters in the Medicare population

To examine the use of inferior vena cava (IVC) filters, we performed a population-based study using a 5% random sample of the United States Medicare population (1.25 million persons). Filter placement and its timing relative to diagnosis of venous thromboembolism (VTE) were determined using both hospital and physician Medicare billing codes after detailed review of large samples of complete individual claims records. Comorbid conditions and mortality were also noted. From July 1986 through June 1989, a total of 806 patients in the sample population received IVC filters. Mortality rates after filter placement were high: 16% during initial hospitalization, 32% within 6 months of filter placement, and 48% after 2 years. However, only 3 (1%) of 423 patients who underwent filter placement without the diagnosis of pulmonary embolism (PE) suffered PE within 1 year of filter placement. Use of IVC filters increased significantly over the study period (p <0.001).Rates of filter placement among the nine census divisions of the United States differed significantly (p<0.001).An East-West trend was notable with the highest rate (37 filters/100,000 enrollees/yr) in New England, as compared with 14 filters/100,000 enrollees/yr in the Pacific Division. No explanation for these regional-differences was evident after patient demographics and comorbidity were examined. Vena cava filters prevent PE for at least 1 year after placement. The frequency of IVC filter use in elderly patients is increasing and varies substantially by region. Although reasons for these trends are unclear, these findings suggest the need for uniform practice guidelines for IVC filter placement.Supported in part by the National Institutes of Aging, grant R0 1 AG 07-146, and by a training grant from the National Library of Medicine (NIH 5 T15 LM07044) to Dr. Birkmeyer.     

Ethanol Ingestion Inhibits Cell-Mediated Immune Responses of Unprimed T-Cell Receptor Transgenic Mice

This paper introduces a transgenic ug) mouse in which the majority of the CWbearing T cells have T-cell receptors that react with ovalbumin (OVA) as a model for ethanol research. Although these Tg animals were bred onto the BALB/c genetic background, a strain generally considered to be nonpreferring in ethanol consumption, we determined that BALB/c mice would consume an ethanol-containing liquid diet, without significant mortality, and assessed alteration of specific immune responses. BALB/c, C57BU6 (B6), or (BALB/c x C57BL6)F1 hybrid (CB6F1) mice were fed LED containing 35,30,25, or 20% ethandaerived calories. Significant mortalii (>40%) was seen only in Wc and pronounced weight loss was seen in BALB/c, B6, CBEIFl mice when they were fed the diet containii the greatest ethanol concentration (LED35). Diets containing lesser amounts of ethanol did not cause mortalii. Liquid diets containing ≥30% ethand-derhred calories significantly impaired the chicken γ-globulbspecnic delayed hypersensitivity responses in Wc, B6, and CB6Flmice without significantly affecting the humoral immune response to sheep red Mood cells. We show that immunization of the Tg mice is not required for the development of a vigorous "debyed hypersensitivity" response to OVA or the I-A'-restricted peptide OVL_323–399 in mice fed standard solid lab chow or liquid control diet. In marked contrast, OVA Tg mice fed ethand show a profound inhibition of this immune response, indicating that ethand-induced inhibition of cell-mediated immunity occurs independently of antigen priming.     

Effect of radiation dose on the development of mixed haemopoietic chimerism following T cell-depleted allogeneic bone marrow transplantation.

The presence of mixed haemopoietic chimerism (MXC) was evaluated by cytogenetic and molecular analysis in 48 patients undergoing T cell-depleted BMT. The dose of total body irradiation (TBI) prescribed to all patients (14.4 Gy) was calculated to compensate for the absence of T cells in the graft. The actual midline dose of TBI received, however, differed significantly depending on the method of TBI administration. Thus, 35 adult patients received an average midline dose of 14.3 Gy, while 13 children received a lower dose of 13 Gy. The incidence of MXC in the adult group, who had received very close to 14.4 Gy to the midline, was 34% (12/35), which is lower than in most reported T cell-depleted series. During follow-up, chimerism remained relatively stable with time but varied between haemopoietic lineages. There was no relationship with relapse. MXC in the 13 children who had received a lower midline TBI dose was significantly higher at 69% (9/13) (p < 0.05) and increased to 90% (9/10) if patients who received additional chemotherapy in their conditioning were excluded (p = 0.001). This suggests that, in terms of marrow ablation, relatively small changes in the dose of TBI may be biologically significant, at least at this dose range. Again, in the lower TBI group MXC was not predictive of relapse.     

Rapid tryptophan depletion improves decision-making cognition in healthy humans without affecting reversal learning or set shifting.

Rapid tryptophan (Trp) depletion (RTD) has been reported to cause deterioration in the quality of decision making and impaired reversal learning, while leaving attentional set shifting relatively unimpaired. These findings have been attributed to a more powerful neuromodulatory effect of reduced 5-HT on ventral prefrontal cortex (PFC) than on dorsolateral PFC. In view of the limited number of reports, the aim of this study was to independently replicate these findings using the same test paradigms. Healthy human subjects without a personal or family history of affective disorder were assessed using a computerized decision making/gambling task and the CANTAB ID/ED attentional set-shifting task under Trp-depleted (n=17; nine males and eight females) or control (n=15; seven males and eight females) conditions, in a double-blind, randomized, parallel-group design. There was no significant effect of RTD on set shifting, reversal learning, risk taking, impulsivity, or subjective mood. However, RTD significantly altered decision making such that depleted subjects chose the more likely of two possible outcomes significantly more often than controls. This is in direct contrast to the previous report that subjects chose the more likely outcome significantly less often following RTD. In the terminology of that report, our result may be interpreted as improvement in the quality of decision making following RTD. This contrast between studies highlights the variability in the cognitive effects of RTD between apparently similar groups of healthy subjects, and suggests the need for future RTD studies to control for a range of personality, family history, and genetic factors that may be associated with 5-HT function.     

MacIntosh-Jones reconstruction for the unstable knee

A group of 45 patients who underwent replacement of a ruptured anterior cruciate ligament with a free graft of one-third of the patellar tendon combined with a lateral extra-articular tenodesis have been reviewed. The average age of the patients was 26.4 years and the mean follow-up period 3.2 years. Stability was achieved in 42 patients (93 per cent), judged on clinical criteria. Overall patient satisfaction was high at 73 per cent and 38 patients (84 per cent) maintained their sporting activity at a social or competitive level. Those who had unsatisfactory results had undergone significant delay before anterior cruciate ligament reconstruction.     

Arthroscopic and endoscopic skills: a method of assessment.

An aptitude test has been designed to assess the psychomotor ability of surgeons under the special conditions and difficulties of endoscopic surgery. Results show increased errors and inferior tracking skill when images are rotated or reflected under test conditions simulating endoscopy. This indicates that more than simple hand-eye co-ordination is required to perform good endoscopic surgery. Interestingly, a proportion of trainee surgeons found adaptation to these altered conditions difficult to master. This aptitude test might usefully identify junior surgeons who would benefit from extra tuition at instructional endoscopic courses. The implications for the selection and training of surgeons are discussed.     

The evolution of benign arterionephrosclerosis from age 6 to 70 years.

Arterionephrosclerosis is diagnosed at autopsy by assessing the severity and extent of certain structural features in the renal cortical arteries seen in tissue sections. These features are characterized by fibrotic intimal thickening and medial shrinkage, a progressive change from the youthful muscular pattern to the elderly sclerotic pattern. Intimal fibrosis can be quantified by expressing intimal thickness as a percentage of the arterial outer diameter (% OD). The magnitude of arterionephrosclerosis, found by averaging the measures of intimal fibrosis seen in a kidney, can be calculated from age and mean blood pressure, using a standard prediction function. This function is a quantitative statement of a fundamentally important principle: just as blood pressure is a continuous variable that can range from low to high levels, arterionephrosclerosis is also a continuous variable that can take any degree of abnormality of arterial structure from minimal to maximal. Furthermore, a correspondence exists between the two quantities so that each can be calculated from the other. In this study, a correlation of 0.966 was found between the observed and the calculated magnitudes of arterionephrosclerosis over 10-year age groups from 25 to 34 years to 65 to 74 years, using group average data within age groups. For individuals, however, the correlations between observed and calculated magnitudes of arterionephrosclerosis were about 0.6 in a former study of elderly subjects and about 0.1 in the subjects aged 6 to 27 years in this study. The average growth rate of arterionephrosclerosis was found to be about 0.25 %OD per year from ages 15 to 54 years, and about 0.13 %OD per year from ages 55 to 70 years; the growth rate did not increase in the oldest age groups when blood pressure averaged higher than blood pressure in more youthful subjects. These and other findings are consistent with the view that the reason a correlation exists between blood pressure and arterionephrosclerosis could be because the magnitude of arterionephrosclerosis is one of the determinants that sets the level of blood pressure. From this perspective, each individual can be viewed as having other determinants of blood pressure, methodologic or biologic, which add to or subtract from the values set by age and arterionephrosclerosis. When subjects are pooled into groups, so that individual determinants balance out, the group average levels of mean blood pressure could be interpreted as reflecting little other than the magnitude of arterionephrosclerosis at each specific age.     

A histochemical study on the distribution of melanin in human oral epithelium at six regional sites.

Oral mucosa from six sites in 95 autopsies was tested for melanin using the Masson-Fontana silver reduction method. Melanin was detected in 51.6% of labial, 46.3% of palatal, 45.3% of buccal, 28.4% of mandibular gingival, 25.3% of lingual and 21.1% of maxillary gingival samples. 93.7% of epidermal samples from the same population were positive. In 24.2% of the subjects there was no detectable melanin at any intraoral site and 4.2% showed activity in all six sites. The mean number of positive oral sites per individual was 2.2. There are thus regional differences in oral epithelial melanocyte activity, but no parallel with the known regional incidence of primary oral melanoma.     

Distribution of carbonic anhydrase activity in neurons of the rat

Certain neurons of dorsal root ganglia (DRG) and some fibers of the sciatic nerve contain histochemically demonstrable carbonic anhydrase activity. Since the distribution of this enzyme throughout the nervous system has not yet been evaluated systematically, we conducted a comprehensive histochemical survey focusing particularly on structures derived from the neural crest and nonneural crest ectoderm. In the peripheral nervous system, we observed carbonic anhydrase activity in some, but not all, neurons of dorsal root, trigeminal, celiac, and myenteric ganglia as well as in glial cells throughout the CNS. Some neurons of the nodose ganglion also showed carbonic anhydrase activity. In all first order sensory ganglia that were studied, the enzyme was found only in large (50 micron or above) and medium (20-50 micron) size neurons; in the case of spinal ganglia, the reactive neurons constituted approximately 30% of the total neuronal population. Of these reactive neurons, 56% were heavily stained and 44% were moderately stained. Several possible roles for neuronal carbonic anhydrase are considered.