Effects of priming duration on retention over the first 1 1/2 years of life

Exposing individuals to an isolated component (a prime) of a prior event alleviates its forgetting. Two experiments with 120 human infants between 3 and 18 months of age determined the minimum duration of a prime that can reactivate a forgotten memory and how long the reactivated memory persists. Infants learned an operant task, forgot it, were exposed to the prime, and later were tested for renewed retention. In Experiment 1, the minimum duration of an effective prime decreased logarithmically with age, but was always longer than the duration of a mere glance. In Experiment 2, the reactivated memory was forgotten twice as fast after a minimum-duration prime as after a full-length one, irrespective of priming delay and infant age. These data reveal that the minimum effective prime duration psychophysically equates the accessibility of forgotten memories. We conclude that priming is perceptually based with effects that are organized on a ratio (log) scale.     

Fibroblast-mediated acceleration of human epithelial tumor growth in vivo.

Transformed fibroblasts coinoculated with epithelial cells accelerated the growth and shortened the latency period of human epithelial tumors in athymic mice. Addition of NbF-1 fibroblasts caused epithelial tumors to grow from five marginally tumorigenic or "nontumorigenic" (nontumor-forming) human tumor cell lines or strains: PC-3 (prostate), WH (bladder), MDA-436 (breast), and cells derived from the ascites fluids of patients with metastatic renal pelvic or prostate cancers. Evidence for the human and epithelial nature of these experimental tumors was provided by histologic, immunohistochemical, Southern and dot-blot hybridization, and cytogenetic analyses. Transformed fibroblasts induced predominantly carcinosarcomas, whereas nontumorigenic fibroblasts (NIH 3T3) and lethally irradiated transformed fibroblasts induced exclusively carcinomas. The fibroblast-epithelial interaction appears to occur bidirectionally and does not result from cell fusion. Because coculture experiments in vitro did not demonstrate an increased cell proliferation, it appears that undefined host factors can influence tumor growth. This tumor model may be useful in drug-screening programs and in mechanistic studies of factors regulating human tumor growth and progression.     

Cytogenetic studies on the in-vitro genotoxicity of 4-nitroquinoline-1-oxide on human-lymphocytes

Using the UV-mimetic mutagen 4-nitroquinoline-1-oxide (4NQO) to induce genetic damage in human cells (lymphoblastoid lines and primary cultures of peripheral blood samples), chromosome aberrations were induced by treating the cells with 4NQO at 1 X 10(-5) M for 24 h. The overwhelming majority of chromosome aberrations was of the chromatid (S + G2) type instead of the chromosome (G1) type. The most common chromatid aberrations were simple breaks, isochromatid breaks, and chromatid exchanges. When the number of chromatid breaks per cell value was used as a measurement for 4NQO sensitivity, lymphoblastoid cells from a xeroderma pigmentosum patient showed the highest sensitivity, followed by the cells of two melanoma patients and normal persons. These preliminary results suggest that 4NQO may be employed to develop an assay system as a biomarker for determining UV sensitivity in the human population.     

The influence of abductor lever-arm changes after shoulder arthroplasty

Clinically, pain relief is usually satisfactory after shoulder arthroplasty, but the range of motion can be limited. The changes of the lever-arms of deltoid and supraspinatus muscles are considered to be important factors influencing postoperative active motion. After excluding patients with muscle weakness resulting from a neurologic condition, patients with chronic rotator-cuff tears, patients who did not follow rehabilitation guidelines, and patients with bilateral arthroplasties, 22 arthroplasty cases remained and were evaluated. Compared with the unaffected side, four radiologic parameters were assessed: (A) offset of humeral head, (B) lateralization of humeral head, (C) acromiohumeral interval, and (D) superoinferior migration of humeral head. The differences were measured and statistically analyzed. In summary: (1) The active and passive range of motion of abduction in scapular plane were 89.5° ± 26.1° and 109.7° ± 25.0°. (2) Parameters A, B, and C statistically changed (p < 0.05). (3) B value of the operated side was reduced below zero in six (27.3%). (4) There was a tendency to create medial shifting and inferior subluxation with the arthroplasty. This had a moderate adverse correlation to the active range of motion (correlation coefficient 0.498). (5) Before normalization for bone size, only C as a single parameter had moderate correlation with motion; after normalization, this decreased. (6) If combined parameters were assessed, A + C had a moderate correlation (correlation coefficient 0.435) with motion. (7) If an accurate anatomic relationship cannot be completely restored, A seemed more significant than any other parameters (p = 0.002); namely, shoulders with a smaller offset had a more limited active range of motion in abduction.     

A questionnaire to assess the generic and disease-specific health outcomes of patients with chronic hepatitis C

A 69-item questionnaire measuring generic functioning and well-being and disease-specific health outcomes was developed and tested using the pre-treatment data from patients with chronic hepatitis C (CHC) participating in two randomized trials of interferon -2b (n = 157). The questionnaire included all eight scales from the SF-36 and measures of nine other generic and disease-specific health concepts. Psychometric tests confirmed the assumptions underlying the construction and scoring of all generic and disease-specific scales. Cross-sectional tests of known groups validity showed that CHC patients scored worse on the generic scales than patients with other chronic conditions and worse than a healthy general population. The generic and disease-specific scale scores were lower in the presence of physical findings of CHC, as hypothesized, but only the physical functioning and bodily pain scales were linked to cirrhosis or extreme alanine aminotransferase (ALT) ratios. This instrument will be useful in studies of health outcome among patients with CHC, a condition whose health burden appears to have been underestimated in studies to date.     

Plasma selenium levels and risk of hepatocellular carcinoma among men with chronic hepatitis virus infection.

Both experimental and epidemiologic studies have linked a low dietary intake of selenium with an increased risk of cancer. The authors examined the association between plasma selenium levels and risk of hepatocellular carcinoma (HCC) among chronic carriers of hepatitis B and/or C virus in a cohort of 7,342 men in Taiwan who were recruited by personal interview and blood draw during 1988-1992. After these men were followed up for an average of 5.3 years, selenium levels in the stored plasma were measured by using hydride atomic absorption spectrometry for 69 incident HCC cases who were positive for hepatitis B surface antigen (HBsAg) and/or antibodies against hepatitis C virus (mostly HBsAg positive) and 139 matched, healthy controls who were HBsAg positive. Mean selenium levels were significantly lower in the HCC cases than in the HBsAg-positive controls (p = 0.01). Adjusted odds ratios of HCC for subjects in increasing quintiles of plasma selenium were 1.00, 0.52, 0.32, 0.19, and 0.62, respectively. The inverse association between plasma selenium levels and HCC was most striking among cigarette smokers and among subjects with low plasma levels of retinol or various carotenoids. There was no clear evidence for an interaction between selenium and alpha-tocopherol in relation to HCC risk.     

The expression of cytokeratin 18 in transitional cell carcinoma comparing with hepatoma

The epithelium in kidneys and urinary bladders contain CK18 as in liver cells. The modulation of cytokeratin 18 during tumor transformation in hepatoma had been previously recognized through a series of biochemical and immunological approaches. A 14 KD hepatoma related molecules was found in the previous studies. We would like to utilize the hepatoma transformation model to study the changes in CK18 in transitional cell carcinoma, using immunoblotting and western blotting techniques. The result is that transitional cell carcinoma retain their CK18 molecule. Furthermore, CK18 related molecules similar to those seen in hepatoma also present in transitional cell carcinoma. The conclusions are transitional cell carcinoma contains CK18 related proteins similar to those seen in hepatoma tissues. We suggest that this element would be responsible for the change during the malignant transformation processes.     

Cost analysis of revision total hip arthroplasty. A 5-year followup study

A stratified, unselected sample of 30 patients who underwent revision total hip arthroplasty between 1990 and 1992 for whom complete clinical and financial data were available was studied. Clinical data included age, gender, diagnosis, length of stay, operative time and blood loss. Financial data included cost of implants, bone graft and accessories, hospital charge, and surgeon reimbursement. Results were compared with the results of an analogous group of 50 patients who underwent revision total hip arthroplasty at the same institution between 1995 and 1997. Cases were classified as simple (involving revision of only acetabular liner and/or femoral head), routine (revision of acetabular and/or femoral components), or complex (major structural graft, antiprotrusio cage, impacted grafting). For patients undergoing routine revision total hip arthroplasty, a dramatic decline of 52% occurred in length of stay during the 5-year span (10.7 days to 5.1 days). The average operative time also declined significantly (238 minutes to 199 minutes) as did the average implant cost ($4349 to $2827). Despite this, the average hospital charge increased 16% ($29,666 to $34,328). There was a significant and dramatic 35% decline in surgeon reimbursement ($3240 to $2178). There was no significant difference in surgeon reimbursement between simple, routine, and complex total hip arthroplasty. Patients who underwent complex procedures had a significantly greater length of stay (7.3 versus 5.1 days) and operative time (297 versus 199 minutes). The hospital charge was dramatically higher for patients undergoing complex procedures ($51,290 versus $34,328) but the surgeon reimbursement was lower on average, although not statistically significant ($1926 versus $2178). There was a significant increase in the number and complexity of revision total hip arthroplasties between the two periods. Significant decreases were achieved in length of stay, operating room time, and implant cost. Benefits from these changes were accrued to the hospital but not the surgeon because hospital costs decreased significantly whereas surgeon reimbursements declined dramatically.