Long-term follow-up of the Günther basket inferior vena cava filter: does mechanical instability cause complications?

PURPOSE

The Günther basket inferior vena cava filter (GBF) has been withdrawn from the market because of its mechanical instability, but a number of patients still live with the device.

METHODS

In a two-center study, we evaluated the long-term follow-up of the GBF, based on clinical data in 78 patients, and on imaging studies including plain radiographs, Doppler ultrasound, angiography, or computed tomography (CT) in 50 patients.

RESULTS

In a mean period of 3 years, pulmonary embolism was diagnosed in five patients (6.4%), with an overall rate of 0.02 embolic episodes per patient per year. None of these patients required hospitalization, and there were no deaths due to pulmonary embolism. Inferior vena cava thrombosis was documented in three patients (3.9%), and occlusive venous thrombosis at the access site in seven patients (9%). Spontaneous migration was documented in 43% of the examined filters and spontaneous disruption in 77%. Dislocated filter fragments were localized by CT in the adjacent retroperitoneum in 11%, in the aortic lumen in 2%, and in a peripheral pulmonary artery in 7%. None of the patients had symptoms attributable to filter migration or disruption.

CONCLUSION

Our results indicate that the rate of clinically relevant complications with the GBF is no higher than with other vena cava filters. Because mechanical instability of the GBF had no clinical consequences, we conclude that patients who live with this device may be observed and treated in a manner similar to patients with other vena cava filters.

Marrow stromal cell commitment to mineralization under the effect of a prolyl hydroxylase inhibitor

Mitochondrial response to the effect of a hydroxylase (PH) inhibitor was tested in marrow stromal cells during stimulation of osteoprogenitor cell (OPC) differentiation. The rationale for this was to explore pathways of regulatory interactions between procollagen synthesis and mitochondrial respiration that could be linked to the commitment of OPCs to mineralization. Stimulated OPCs exposed to the PH inhibitor cis-hydroxyproline (cis-HP), compared to the noninhibiting isomer trans-HP, for 11 days showed a dose-dependent decrease in cell proliferation, the surviving cells showed increased alkaline phosphatase activity. Trans-HP did not influence the cis-HP effect on ALP and on proliferation arrest. Short time exposures, 2-3 days, to cis-HP at different periods suggested that Days 0-3 and 3-5 were critical for the commitment to Day 21 mineralization of OPCs. On Days 0-3 cells were most sensitive to cis-HP, since on Day 11, 8 days after removal of cis-HP, they were too scarce to be counted by the staining method. However, the presence of 5.0 mM cis-HP in the cultures during Days 3-5 has induced on Day 21 close to 24-fold more mineralization/cell than controls, compared to the trans-HP effect, which was only close to 3-fold. The presence of cis-HP in the cultures on Days 0-3 has augmented the mitochondrial Day 3 retention of rhodamine 123 (Rho) in the stromal cells, relative to controls, compared to the presence of trans-HP. However, the presence of cis-HP during Days 3-5 or 3-6 resulted in lower Day 5 Rho retention, relative to controls, which was not significantly different from the retention that resulted from trans-HP. Since Rho retention is related to the final result of aerobic respiration level, these results are interpreted as a cis-HP inhibitory effect on procollagen peptidyl-proline hydroxylation, which may in turn release oxygen surpluses, to be available for mitochondrial consumption. The fall in Rho retention responses to cis-HP between Days 0-3 and 3-5 is suggesting either abrupt decrease in proline hydroxylation or poor mitochondrial sensitivity to oxygen in Day 3-5 cultures.

Induction of osteoprogenitor cell differentiation in rat marrow stroma increases mitochondrial retention of rhodamine 123 in stromal cells

Bone marrow stromal cells contain colony forming cells with the potential to differentiate into osteoprogenitor (OPC) cells. OPC-stimulation medium, containing dexamethasone, ascorbate, and beta-glycerophosphate is widely used to recruit OPCs in culture. Cultures were incubated 24 h with rhodamine 123 (Rho), on different days, to examine the effect of the OPC-stimulation medium on the mitochondrial membrane potential of stromal cells. Cultures grown in both ordinary medium (DMEM with 15% FCS) and OPC-stimulation medium showed 2 Rho retention peaks on days 3-4 and 10-11. Between days 5 and 10 there was a drop in Rho retention/cell. OPC-stimulation medium increased Rho retention by at least twice the amount relative to ordinary medium, and has quadrupled it on day 7. Incubation with Rho concentrations above 5.0 micrograms/ml inhibited the portion of increased Rho retention which was contributed by the OPC-stimulation medium. Prolonged exposure to 0.1, 1.0, and 10.0 micrograms/ml Rho for 12 days only slightly increased day 12 ALP activity/cell, had no effect on day-21 mineralization and only the high dose, 10.0 micrograms/ml, doubled stromal cell proliferation. Under 24 h incubation Rho concentrations of 1.0 microgram/ml and below can serve as a marker for mitochondrial membrane potential in differentiating stromal cells. The results indicate that under both culture conditions stromal cell mitochondria undergo cycles of high and low membrane potential states and that the OPC-stimulation medium constantly maintains an elevated membrane potential relative to ordinary medium.

Studies of the levamisole inhibitory effect on rat stromal-cell commitment to mineralization

The ability of Levamisole to decrease mineralization in skeletal tissue is usually related to its effect on alkaline phosphatase (ALP). However, Levamisole is also suspected to diminish mineralization by an additional mechanism which is unrelated to the ALP control of apatite crystal growth. To delineate the time in differentiation during which Levamisole inhibits mineralization, a tissue culture model system of bone marrow stromal cells was used. Secondary cultures of stromal cells were propagated in osteoprogenitor cell (OPC) induction medium for three weeks, followed by measurement of calcium precipitation. In situ ALP assays at pH 7.6 were also performed. When cells were cultured with 0.2 mM Levamisole for three weeks, Day 20 values of calcium precipitates were lower than in controls, but Day 20 ALP values were paradoxically higher. The correlation between calcium and ALP within each group was low. The correlation slightly improved, in uninhibited cultures, when Day 21 calcium values were matched with earlier Day 12 ALP values. This suggested the existence of a Levamisole-sensitive mechanism for mineralization inhibition effective prior to the culture's mineralization stage. To focus on this early effect on mineralization Levamisole was added to stromal cultures on different days and removed on Day 12. Levamisole decreased Day 21 mineralization when added on Days 0, 3, 5, and 7, but not when added on Day 9. The Levamisole-induced inhibition of mineralization was accompanied by an increase in Day 12 ALP specific activity, compared to controls, when added from Day 5 and thereafter. The results indicate that part of the ability of stromal cells to mineralize is determined during the first week of culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Selection of malonate-resistant stromal cell-derived osteoprogenitor cells in vitro

Bone marrow stromal cells give rise to osteoprogenitor cell (OPC) colonies, with characteristic mineralized bone nodules in vitro. During differentiation, OPCs in the culture are surrounded by heterogeneous populations of various cell lineages and by different OPC differentiation stages. In the present study, attempts were made to increase the homogeneity of OPCs in culture. The reliance on energy metabolism restricted to glycolysis, which is specific to the premineralizing skeletal cells, was tested as a selectable marker for cells in this stage. Day 12 alkaline phosphatase (ALP) and day 20-21 calcium precipitates were used as early and late OPC differentiation markers. Malonate, a competitive inhibitor of succinate dehydrogenase, was added to the OPC stimulation medium, to interfere with the Krebs cycle-dependent energy metabolism operating in most of the stromal cells. OPCs that entered the stage of energy metabolism restricted to glycolysis were expected to become malonate resistant. Malonate showed dose and time dependence, 10 mM malonate added on day 3, decreased day 12 ALP activity/well to the lowest level. Variations in time and length of exposure to malonate used during the first 12 days of differentiation showed an inverse correlation between specific ALP activity and cell yield. Malonate-treated variations of specific ALP and of cell yield indices were up to 30- to 40-fold larger than variations within day 21 calcium precipitates. Thus, calcifying cells were almost unchanged relatively to noncalcifying cells. These results indicate that malonate-resistant cells are mostly selected, rather than induced, to differentiate by malonate. The results also show that stromal derived OPCs undergo a similar biochemical stage as in chondrocytes.

Vitamin A concentration in amniotic fluid and maternal serum related to neural-tube defects

The vitamin A concentration of amniotic fluid and maternal serum was measured during the second trimester of pregnancy in 106 women, 12 of whom had a baby with a neural-tube defect. In these 12 pregnancies the amniotic fluid vitamin A concentration was significantly higher than in 94 normal pregnancies. There was a highly significant correlation between amniotic fluid vitamin A and both zinc and alpha-fetoprotein (AFP) levels. The maternal serum vitamin A levels were also significantly related to serum zinc levels. Women with a raised serum AFP level, but a normal baby, had significantly higher amniotic fluid vitamin A levels and significantly lower serum vitamin A levels compared with those in women with normal serum AFP levels.

The effect of palliative surgery on the survival of central nervous system malformations

Patients suffering from hydrocephalus alone or in combination with spinal defect were investigated in this retrospective study. The cases were grouped to those who did not have any treatment to relieve the symptoms of hydrocephalus and to those who receive certain palliative therapy. Comparisons were made between the groups regarding the life-span and the incidence of secondary complications. The life-span showed a close agreement within the groups, but the occurrence and the severity of secondary complications were found to be less in the treated group. While the reasons are acceptable which are given to select the patients for the initial closure of the spinal defect there seems to be no justification in with-holding palliative surgery for the treatment of hydrocephalus.

Effects of oral contraceptives on human plasma vitamin-A levels

Vitamin-A levels have been determined in healthy non-pregnant women and in women taking synthetic steroids to suppress ovulation. A significant increase has been found in those receiving oral contraceptives. Further work is necessary to determine whether this may affect the fetus in patients who become pregnant shortly after discontinuing oral contraception.