An ectopic pregnancy embedded in the myometrium of a previous cesarean section scar.
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Adult↗
Biomedical subjects
T C Chen
Publications and source records attributed to T C Chen.
The transfacet pedicle-sparing approach for thoracic disc removal: cadaveric morphometric analysis and preliminary clinical experience.
A number of operative techniques have been described for the treatment of herniated thoracic discs. The transfacet pedicle-sparing approach allows for complete disc removal with limited spinal column disruption and soft-tissue dissection. Fifteen cadaveric spinal columns were used for evaluation of exposure, development of thoracic microdiscectomy instrumentation, and establishment of morphometric measurements. This approach was used to remove eight thoracic discs in six patients. Levels of herniation ranged from T-7 through T-11. Preoperatively, all patients had moderate to severe axial pain, and three (50%) of the six had radicular pain. Myelopathy was present in four (67%) of the six patients. Through a 4-cm opening, the ipsilateral paraspinal muscles were reflected, and a partial facetectomy was performed. The disc was then removed using specially designed microscopic instrumentation. Postoperatively, the radiculopathy resolved in all patients. Axial pain and myelopathy were completely resolved or significantly improved in all patients. The minimal amount of bone resection and muscle dissection involved in the operation allows for: 1) decreased operative time and blood loss; 2) diminished perioperative pain; 3) shorter hospitalization time and faster return to premorbid activity; 4) avoidance of closed chest tube drainage; and 5) preservation of the integrity of the facet-pedicle complex, with potential for improvement in outcome related to axial pain. This technique appears best suited for the removal of all centrolateral discs, although it has been used successfully for treating a disc occupying nearly the entire ventral canal. The initial experience suggests that this approach may be used to safely remove appropriately selected thoracic disc herniations with good results.
Adult↗
T-cell--mediated autologous hepatocytotoxicity in patients with chronic hepatitis C virus infection.
Virus-specific cytotoxic T lymphocytes (CTLs) have been suggested to be responsible for the liver injuries in patients with hepatitis C virus (HCV) infection. However, there has been no report of direct evidence to substantiate this hypothesis. In this study, we performed in vitro autologous hepatocytotoxicity assay in 45 patients to examine a possible role of CTLs to HCV-infected live cells. The data were correlated with histology activity index of liver biopsy specimens. Lymphocyte subsets and hepatocyte expression of human major histocompatibility complex antigens class I and class II (HLA-I and HLA-II) were also evaluated. The immunohistochemical study showed more prominent HLA-I expression than HLA-II on hepatocytes (mean score +/- SEM:2.34 +/- 0.11 vs. 0.42 +/- 0.08; P < .01). The lymphocyte subset analysis showed that CD8+ T cells were dominant in the lobular areas showing spotty necrosis, whereas CD4+ T cells were prominent in the portal and periportal areas (P < .01). Most patients had a significant T cell-mediated cytotoxicity to hepatocytes as compared with non-T cells (percentage cytotoxicity +/- SEM:46.4 +/- 2.3 vs. 13.8 +/- 2.7; P < .001). T cell-mediated hepatocytotoxicity had a linear correlation with HAI (P < .05). The T cell-mediated cytotoxicity could be blocked by anti-CD8 (43.7% vs. 18.5%, P < .05) but not by anti-CD4 or anti-HLA-II monoclonal antibodies. These findings strongly suggest that HLA-I-restricted, CD8+ T cell-mediated hepatocytotoxicity is an important pathogenetic mechanism in patients with chronic HCV infection.
Adult↗
Compensation for the interracial variance in the cutaneous synthesis of vitamin D.
We investigated the homeostatic compensation for the lower cutaneous synthesis of vitamin D in heavily melanized persons. Vitamin D2 (50,000 IU) was administered in a single oral dose to 24 young adults, 12 blacks and 12 whites, matched for age, gender, and socioeconomic status. We also included a group of eight healthy elderly white adults as representatives of a population with a nonracial mechanism for decreased cutaneous vitamin D synthesis. Plasma determinants were performed under basal conditions and at 6, 10, and 24 hours after vitamin D intake. Basal 25-hydroxyvitamin D (25-OH-D) levels were significantly lower in blacks (12.5 +/- 2.2 ng/ml (mean +/- SEM)) and in elderly whites (19.2 +/- 1.9 ng/ml), compared with young whites (30.2 +/- 3.0 ng/ml (p < 0.0001)); levels of basal 1,25-dihydroxyvitamin D (1,25(OH)2 -D) did not differ between groups. The vitamin D blood curve was similar between groups after the oral vitamin D2 load. Increases in 25-OH-D were 91.7 +/- 15.9% in blacks, 18.8 +/- 5.2% in young whites, and 28.6 +/- 6.9 in elderly whites; 1,25(OH)2-D levels increased slightly and did not differ between groups, although in blacks the change over time was significant (p < 0.05). As a whole, the study populations exhibited a strong relation between basal and peak 25-OH-D (r = -0.80; p < 0.001). Levels of intact parathyroid hormone and serum calcium of blacks and young whites did not differ within or between groups throughout the test.(ABSTRACT TRUNCATED AT 250 WORDS)
Administration, Oral↗
Pilot study of topical calcitriol (1,25-dihydroxyvitamin D3) for treating psoriasis in children.
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Adolescent↗
A parathyroid hormone antagonist stimulates epidermal proliferation and hair growth in mice.
The biologic action of parathyroid hormone (PTH)-related peptide (PTHrP) in normal skin was investigated in cultured human keratinocytes and in SKH-1 hairless mice. The results indicate that the PTHrP agonists human PTHrP-(1-34) and PTH(1-34) are potent inhibitors of epidermal cell proliferation. [Nle8,18,Tyr34]bovine PTH-(7-34)-amide, an antagonist of the PTH/PTHrP receptor, blocked the inhibitory effect of PTH-(1-34) in cultured keratinocytes. In the SKH-1 mice, PTH-(7-34) caused a 244% increase of [3H]thymidine incorporation into isolated epidermal DNA and 246% and 180% increases in the number and length of hair shafts, respectively. Thus, PTH and PTHrP may play an important role in the normal physiology of skin, and their agonists and antagonists have potentially wide therapeutic applications in the treatment of hyperproliferative skin disorders and aging skin and could also be effective in stimulating and maintaining hair growth.
Animals↗
Protein kinase C inhibitors induce apoptosis in human malignant glioma cell lines.
Previous work has demonstrated the importance of the protein kinase C (PKC) system in regulating glioma growth, and has led to clinical trials utilizing PKC inhibitors as adjuncts in the therapy of patients harboring malignant gliomas. This study was performed to explore the possibility that inhibition of PKC in gliomas was triggering an apoptosis signal. Glioma cell lines were treated with PKC inhibitors staurosporine (10 nM), and tamoxifen (10 microM). DNA from cells treated with each of these drugs exhibited a 'ladder' pattern of oligonucleosome-sized fragments characteristic of apoptosis, thus suggesting that in glioma cells, these drugs may be cytocidal in action.
Alkaloids↗
New device for biofragmentable anastomotic ring in low anterior resection.
PURPOSE: The biofragmentable anastomotic ring (BAR) is now accepted as an alternative anastomotic method to handsewn and stapled anastomosis in colonic surgery. However, for a short rectal stump in a narrow pelvis, it is rather difficult to use the BAR in a low anterior resection. METHOD: To overcome the difficulty, we designed and used a BAR-adapter to facilitate biofragmentable ring anastomosis following low anterior resection in eight patients with rectal cancers. RESULTS: There was no case in our series having received conversion to other methods. There was no significant complication associated with this technique. CONCLUSION: With the BAR-adapter, the applicability of the BAR can be greatly expanded in colorectal anastomosis following low anterior resection.
Aged↗
A possible genetic defect in 25-hydroxylation as a cause of rickets.
We examined two siblings who had severe rickets at ages 2 and 7 years, respectively, despite a history of adequate vitamin D intake. The patients' sera had calcium concentrations at the lower limits of normal, low phosphate concentrations, elevated alkaline phosphatase activity, and low levels of 25-hydroxyvitamin D. Treatment with high doses of vitamin D2 resulted in resolution of the biochemical abnormalities and radiographic deformities; pharmacologic doses of vitamin D2 were required to maintain normal concentrations of 25-hydroxyvitamin D in the serum even though vitamin D absorption was normal. These children may have a genetic defect of the 25-hydroxylation step in vitamin D activation.
25-Hydroxyvitamin D 2↗
Headache recurrence in pregnant women with migraine.
The goal of this study was to evaluate to what extent pregnancy influences headache recurrence in women with a diagnosis of migraine at, or before, their first prenatal visit. Data from the large, prospective Collaborative Perinatal Project of 55,000 pregnancies were reviewed. Less than 2% of women in the sample of first study pregnancies were considered to have migraine at their initial prenatal visit (n = 508). Of the 484 women with a complete data set, 17% experienced complete cessation of headache throughout pregnancy and another 62% experienced two or fewer headaches in the third trimester. These observations lead to the conclusion that many migraineurs (79% in this sample) experience improvement in headache recurrence during pregnancy. Only 21% experienced no improvement at all. No demographic or obstetrical factor was associated with headache improvement.
Female↗
Characterization of the translocation process of vitamin D3 from the skin into the circulation.
The cutaneous synthesis of vitamin D3 and the subsequent translocation of vitamin D3 into the circulation are two key steps in the vitamin D endocrine system. To study the kinetic aspects of cutaneous synthesis and translocation of vitamin D3, both in vitro and in vivo chicken models have been developed. To assess the capacity of chicken skin to generate vitamin D3, the concentrations of 7-dehydrocholesterol (7-DHC) in different skin areas were determined. It was found that the highest concentration of 7-DHC was in the leg skin (3524 +/- 937 ng cm-2), which was about 30 times greater than that in the back (120 +/- 62 ng cm-2). Whole body exposure of chickens to UV-B radiation (0.5 J cm-2) resulted in the production of previtamin D3 (preD3) in the skin of the legs and feet (43 +/- 7 and 54 +/- 17 ng cm-2, respectively), whereas no preD3 was detected in the back skin. In vitro, at 40 C, the forward (k1) and reverse (k2) rate constants of the preD3<-->vitamin D3 reaction in the leg skin were greatly increased compared to those in n-hexane (k1, 0.367 vs. 0.0369 h-1; k2, 0.042 vs. 0.0059 h-1). In vivo, the determined rate constants k1, k2, and k3 for the consecutive reactions preD3<-->vitamin D3-->vitamin D3 were 0.257, 0.034, and 0.114 h-1, respectively. To evaluate the circulating concentration of vitamin D3 in response to UV-B radiation, chicken legs were irradiated. The time course revealed a 4-fold increase in the circulating concentration of vitamin D3, with a peak about 30 h postradiation. No appreciable amount of preD3 could be detected in the circulation in the early hours after UV-B radiation, suggesting the existence of a process responsible for the specific translocation of vitamin D3 from the skin into the circulation.
Animals↗
Brain stem compression secondary to adipose graft prolapse after translabyrinthine craniotomy: case report.
Three cases of fat graft prolapse into the cerebellopontine angle with clinical deterioration are presented. These patients had undergone translabyrinthine craniotomy for cerebellopontine angle tumors and had autologous abdominal fat strips placed to obliterate the dural defect and the mastoid cavity. Two patients suffered significant morbidity, and one patient died. Clinical presentation, computed tomographic scan findings, methods of treatment, and avoidance of this complication are discussed.
Adipose Tissue↗
Multifocal inflammatory leukoencephalopathy associated with levamisole and 5-fluorouracil: case report.
Levamisole and 5-fluorouracil have now become the standard chemotherapeutic regimen for patients with Stage III colon carcinoma. A case of multifocal inflammatory leukoencephalopathy secondary to levamisole alone or combination of levamisole and 5-fluorouracil is reported. Magnetic resonance imaging with gadolinium demonstrated multifocal contrast-enhancing frontal, parietal, occipital, and periventricular white matter lesions. A stereotactic biopsy revealed reactive gliosis and macrophage infiltration, without evidence of metastatic tumor. Despite continuation of 5-fluorouracil, resolution of contrast-enhancing lesions on magnetic resonance imaging without further neurological sequelae occurred when levamisole was stopped. The patient died with evidence of systemic metastasis 6 months later. Autopsy examination of the brain revealed multifocal demyelinating lesions, with no evidence of metastatic tumor. Immunoperoxidase studies of demyelinated lesions demonstrated infiltrating macrophages strongly positive for Class II antigens, interleukin-6, and interleukin-1 alpha. Surrounding astrocytes were positive for granulocyte macrophage colony-stimulating factor. Small numbers of perivascular T cells were present. This patient represents the first autopsy documented case of levamisole associated multifocal inflammatory leukoencephalopathy.
Aged↗
Cranioplasty with the Medpor porous polyethylene flexblock implant. Technical note.
The authors describe the use of a porous polyethylene Flexblock implant for cosmetic cranioplasty. The implant may be used to cover any small- or medium-sized (< 8 cm) cranial defect, offering similar cosmetic results to standard alloplast cranioplasty while decreasing operation time. The porous implant design permits ingrowth of soft tissue and bone to increase implant strength and decrease the risk of infection. The Flexblock alloplast has been utilized in 25 cases with excellent cosmetic results and no implant-related complications.
Biocompatible Materials↗
Expression of 25-hydroxyvitamin D3-24-hydroxylase mRNA in cultured human keratinocytes.
It is well documented that 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25[OH]2D3), the most active vitamin D metabolite, inhibits epidermal keratinocyte proliferation and promotes differentiation. 1 alpha,25(OH)2D3 can be produced in keratinocytes from 25-hydroxyvitamin D3 by the enzyme 25-hydroxyvitamin D3-1 alpha-hydroxylase (1-OHase). Hydroxylation of 1 alpha,25(OH)2D3 by 25-hydroxyvitamin D3-24-hydroxylase (24-OHase), the first step in the catabolic pathway of 1 alpha,25(OH)2D3 could significantly reduce the intracellular concentration of 1 alpha,25(OH)2D3. Therefore, the expression of 24-OHase could have a critical regulatory role in 1 alpha,25(OH)2D3-dependent gene expression. As a first step to examine this possibility, the steady state level of 24-OHase mRNA in cultured human keratinocytes (CHK) was investigated. 24-OHase mRNA was not detected in control CHK. 1 alpha,25(OH)2D3 caused a dose- and time-dependent increase in 24-OHase mRNA level. The highest accumulation of 24-OHase mRNA was observed in CHK treated with 0.1-1 microM 1 alpha,25(OH)2D3. The level of 24-OHase mRNA reached a plateau 12-24 hr after 1 alpha,25(OH)2D3 treatment. 1 beta,25-dihydroxyvitamin D3, the stereoisomer of 1 alpha,25(OH)2D3, failed to induce 24-OHase mRNA expression significantly. In addition to 24-OHase mRNA, a 1.0-kb mRNA hybridized strongly with both rat and human 24-OHase cDNA probes. The origin of this 1.0-kb message is unknown at present, however, it was regulated by 1 alpha,25(OH)2D3. These results demonstrate that 1 alpha,25(OH)2D3 up-regulates the expression of 24-OHase mRNA, and this may be an important first step in the initiation of catabolism of 1 alpha,25(OH)2D3 in human keratinocytes.
Calcitriol↗
Complex technical methodologies and their applications in the surgery of intracranial meningiomas.
As neurosurgery moves into the twenty-first century, improved visualization/localization techniques, neuromonitoring, and advanced instrumentation will become standards of care for all intracranial procedures. This article has focused on current available technologies that can be used to facilitate operations on intracranial meningiomas. Preoperative anatomic localization with MR imaging, CT, MR angiography, and angiography are standard techniques. Preoperative functional assessments with MR imaging, magnetic source imaging, PET, and functional MR imaging are crucial to recognize and preserve eloquent adjacent cortex. Pathologic correlations with preoperative imaging (i.e., MR imaging) may help to predict the histopathology. Perioperative rehearsal of the operation can be performed. Intraoperative anatomic localization is important to minimize the craniotomy, dural opening, and passage through normal neural structures. An impressive array of new technologies are currently available, including real-time ultrasonography, frame-based stereotaxy (CT, MR imaging PET), frameless stereotaxy (acoustic localization, neuronavigators, real-time visualization), robotics, neuroendoscopy, and intraoperative dye administration. Increased understanding of the function and individual variability of the human cortex underscores the importance of intraoperative functional localization by electrocorticography and optical imaging. Continuous intraoperative neuromonitoring of sensory (SSEPs, BAERs, visual evoked potentials) and motor evoked potentials is now standard during many intracranial procedures. Complex adjunctive instrumentation, such as the ultrasonic aspirator and the laser, are part of the contemporary armamentarium for meningioma surgery. As we have stated in a previous article, "Developmental trends imply realization of three major directions of technical neurosurgery: (1) precise preoperative simulation, (2) minimization or avoidance of transcranial operative corridors, [and] (3) increased refinement of technical adjuvants--both physical and molecular." The end point of these technical advances is to improve precision and safety and will enhance the outcome in each surgical procedure so that one day we will be able to operate on patients with intracranial lesions with minimal morbidity.
Brain↗
An update on the vitamin D content of fortified milk from the United States and Canada.
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Adult↗
Parathyroid hormone transport effects and hormonal processing in primary cultured rat proximal tubular cells.
The development of satisfactory cell culture models for the study of parathyroid hormone (PTH)-induced inhibition of Pi transport has proven difficult. Using subcellular fractionation techniques we investigated the response of primary cultures of rat proximal tubular cells to PTH-(1-34). Specific binding of 125I-bPTH-(1-34) occurred at 2 degrees C. After 5 min of rewarming, trypsin-releasable radioactivity decreased from 90 to 50%, indicating internalization of the ligand. Cell disruption, followed by density centrifugation with 17% Percoll either directly after binding at 2 degrees C or post-rewarming for 20 min, showed a shift of 125I label from the plasma membrane (5'-nucleotidase) to lysosomal fractions (beta-D-glucosaminidase), confirming the sequential occurrence of cell surface binding, internalization and transport to lysosomes of 125I-bPTH-(1-34). Reculture at 37 degrees C revealed steady accumulation of trichloroacetic acid-soluble radioactivity in the medium, indicating degradation of 125I-bPTH-(1-34). Phosphate transport in the absence of sodium was minimal. Incubation of the cells with bPTH-(1-34) resulted in up to 50% inhibition of sodium-dependent phosphate transport. Prior phosphate depletion abrogated the response to PTH.
Animals↗