Müller cell and neuronal remodeling in retinal detachment and reattachment and their potential consequences for visual recovery: a review and reconsideration of recent data

Recent evidence suggests that the adult mammalian retina is far more plastic than was previously thought. Retinal detachment induces changes beyond the degeneration of outer segments (OS). Changes in photoreceptor synapses, second- and even third-order neurons may all contribute to imperfect visual recovery that can occur after successful reattachment. Changes that occur in Müller cells have obvious effects through subretinal fibrosis and proliferative vitreoretinopathy, but other unidentified effects seem likely as well. Reattachment of the retina induces its own set of responses aside from OS re-growth. Reattachment halts the growth of Müller cell processes into the subretinal space, but induces their growth on the vitreal surface. It also induces the outgrowth of rod axons into the inner retina.     

Selection of the first-time dose in humans: comparison of different approaches based on interspecies scaling of clearance

The authors describe four approaches to selecting a safe starting dose for humans in clinical drug trials based on interspecies scaling of clearance. Human clearance was predicted by scaling for 10 example drugs for which animal clearance values were available in the literature. The predicted human clearance values were then used to select the estimated starting dose in humans. These doses were then compared with the actual doses given to humans during clinical trials. All four approaches used to estimate the first-time dose in humans provided values that were within the dose range given to humans from Phases I to III. This work demonstrates that animal pharmacokinetic data can be used to estimate a suitable human starting dose, provided the data have been obtained from a dose that produces no adverse effects.     

Assessing the toxicity of dodecylbenzene sulfonate to the midge Chironomus riparius using body residues as the dose metric

Dodecylbenzene sulfonate (DBS) is a component of linear alkylbenzene sulfonate (LAS), an anionic surfactant, mainly used in household detergents. Due to the large quantity of DBS in use, there is concern over adverse environmental effects. This work examined the toxicokinetics and toxicity of the 2-phenyl isomer of dodecylbenzene sulfonate in 4-d, 10-d, and partial life-cycle tests on the midge, Chironomus riparius, exposed to aqueous solutions. Toxicokinetics were determined in 10-d uptake and 5-d elimination tests. The toxicokinetics were based on parent compound concentration in water and yielded an uptake coefficient (ku) of 17.5 (14.87-20.20) ml/g/h, an elimination rate constant (ke) of 0.073 (0.062-0.085) per h, a bioconcentration factor (BCF) of 56 to 240, and a half-life (t 1/2) of 9.5 (8.0-11.0) h. Biotransformation measurements did not reveal evidence for DBS metabolism. Thus, body residues, determined in the toxicity study, represent parent compound. In toxicity tests, 4- and 10-d LR50s (the body residue required to cause 50% mortality) in live midges were 0.72 (0.65-0.79) and 0.18 (0.08-0.42) mmol/kg, respectively. Thirty-day LR50s were 0.18 (0.09-1.64) and 0.21 (0.15-0.39) mmol/kg in duplicate studies. Of the sublethal endpoints, only developmental time increase was significant, with the lowest-observed-effect residues of 0.085 (0.067-0.105) and 0.100 (0.087-0.114) mmol/kg for male and female midges, respectively. Deformities in surviving larvae were also observed as chronic responses for body residues exceeding the 30-d LR50. The body residues required for mortality suggest that DBS acts like a polar narcotic in the midge.     

Relationship of hospital volume to outcome in cardiac surgery programs in California

There are more than 120 cardiac surgery programs in California. More than half perform less than 200 coronary artery bypass graft (CABG) procedures per year. This study queried the state of California discharge abstract database to analyze the relationship between annual procedural volume and outcomes of all 119 nonfederal hospitals performing cardiac surgery during 1997 through 1999. Unadjusted in-hospital mortality for CABG surgery was 3.91 per cent (923 of 23,619) in hospitals performing fewer than 200 procedures per year and 2.09 per cent (496 of 23,704) in hospitals performing > or = 500 procedures annually (P = 0.001 by Chi-square). Similar findings were noted for CABG + valve and/or aneurysm and for valve procedures. Risk-adjusted CABG data obtained from 78 of 119 hospitals found that a significant difference persisted between a volume of < 200 and > or = 200 procedures per year (P = 0.03 by t test). There was wider variation in outcome among lower-volume hospitals. However, many low-volume providers had excellent results. It is concluded that although volume is clearly related to outcome patient-related factors and process variables may be more important. Performance improvement programs should be developed to improve communication between providers with differing outcomes.     

Vrms/T quantitation in patients with lumbar spinal stenosis

Thirty consecutive patients with clinical and radiographic findings consistent with lumbosacral root injury were evaluated. Electrodiagnostic examinations included determination of root mean square (Vrms)/turns (T) values. Vrms/T values > or =1 are consistent with chronic neurogenic injury and have been correlated with increase in fiber density. Radiographic studies were independently classified as having severe (group I; n= 8), mild (group II; n=11), or no lumbar spinal stenosis (group III; n=11). Abnormal Vrms/T values were present in all 8 patients in group I in comparison to 0/11 in group II and 2/11 in group III (p<0.0001 and 0.0007 respectively in comparison to group I). In 5/8 patients in group I, Vrms/T values provided unique information. Large amplitude motor units were also present more frequently in group I in comparison to the other groups (p<0.02). This study indicates Vrms/T values can be helpful in the electrodiagnostic evaluation of patients with lumbosacral radiculopathies, particularly where chronic multilevel radicular injury might be expected such as in lumbar spinal stenosis.     

Hepatic artery thrombosis after liver transplantation and genetic factors: prothrombin G20210A polymorphism

Hepatic artery thrombosis (HAT) after liver transplantation is associated with a high incidence of graft failure. The incidence ranges between 2% and 25%, with an overall incidence of approximately 7%. Different risk factors have been associated, but the participation of genetic factors in the cause of HAT is less well studied. A single-base change (G to A) at position 20210 in the 3' untranslated region of the prothrombin gene is associated with increased plasma levels of prothrombin and might therefore increase the risk for thrombosis. We reviewed our HAT experience in 11 years at Medical College of Virginia hospitals of 491 patients undergoing 533 liver transplantations. There were 14 liver grafts with documented HAT (2.62%) in 13 patients. Prothrombin G20210A polymorphism was found in the DNA obtained from 2 of 14 liver allograft tissues (14.2%) but not in the DNA from leukocytes obtained from the peripheral blood of recipients with HAT.     

Phase III quality-of-life study results: impact on patients' quality of life to reducing xerostomia after radiotherapy for head-and-neck cancer--RTOG 97-09

PURPOSE: To determine whether prevention of hyposalivation after curative radiotherapy (RT) to the head and neck improves patients' quality of life (QOL). METHODS AND MATERIALS: Patients were to receive at least 50 Gy to 50% of the volume of the major salivary glands, provide unstimulated and stimulated saliva samples, and complete the University of Washington head-and-neck QOL tool before RT and 3 and 6 months after RT. Patients were randomized to receive pilocarpine 5 mg or placebo q.i.d. RESULTS: A total of 249 patients was randomized between March 1998 and January 2000. Of these, 214 were eligible for QOL analysis. Patients were evenly distributed between arms by race, gender, tobacco use, tumor site, T stage (50% T2-T3), and salivary function. A Karnofsky performance status of 90% was more common in the pilocarpine arm. Twenty percent of the patients on the pilocarpine arm and 29% of the patients on the placebo arm were taking nutritional supplements. The placebo arm patients had greater mouth pain and chewing difficulties. Compliance for the QOL tool at 3 and 6 months was 65% and 50%, respectively. Despite statistically significant (p = 0.047 and p = 0.049, respectively) preservation of salivary function in the pilocarpine arm, patients on the pilocarpine arm reported difficulties with swallowing (75%), activity (80%), hyposalivation (64%), and taste (81%). No difference was noted between arms at 3 months in mucositis scores, with both arms demonstrating increased requirement for oral nutrients. CONCLUSION: Objective prevention of hyposalivation did not affect patients' assessment of salivary function or QOL because of the greater impact mucositis plays in QOL after RT.     

Induction of CD8 T-cell-Ifn-gamma response and positive clinical outcome after immunization with gene-modified allogeneic tumor cells in advanced non-small-cell lung carcinoma

Large tumor burdens in advanced non-small-cell lung carcinoma (NSCLC) are thought to be immunosuppressive. To determine whether CD8-mediated immune responses could be elicited in stage IIIB/IV NSCLC patients, 14 subjects were immunized several times with allogeneic NSCLC cells transfected with CD80 (B7.1) and HLA-A1 or A2. Patients enrolled were matched or unmatched at the HLA A1 or A2 locus and their immune response compared. Immunization significantly increased the frequencies of interferon-gamma secreting CD8 T cells in all but one patient in response to ex vivo challenge with NSCLC cells. The CD8 response of matched and unmatched patients was not statistically different. NSCLC reactive CD8 cells did not react to K562. Clinically, five of 14 patients responded to immunization with stable disease or partial tumor regression. The study demonstrates that CD8 Ifn-gamma responses against nonimmunogenic or immunosuppressive tumors can be evoked by cellular vaccines even at advanced stages of disease. The positive clinical outcome suggests that nonimmunogenic tumors may be highly susceptible to immune effector cells generated by immunization.     

The incidence of lung carcinoma after surgery for breast carcinoma with and without postoperative radiotherapy. Results of National Surgical Adjuvant Breast and Bowel Project (NSABP) clinical trials B-04 and B-06

BACKGROUND: In the current study, the authors compared the incidence of subsequent primary lung carcinoma in patients with breast carcinoma who received radiotherapy as part of their treatment and in those patients who did not. The patients were participants in two large National Surgical Adjuvant Breast and Bowel Project (NSABP) breast carcinoma trials, B-04 and B-06, which prospectively randomized women to either undergo surgery alone or to undergo surgery and postoperative radiotherapy. METHODS: The NSABP trial B-04 (1971-1974) randomized patients to undergo radical mastectomy versus total (simple) mastectomy and radiotherapy to the chest wall, axilla, and supraclavicular and internal mammary lymph node areas. For patients with a clinically uninvolved axilla, there was a third randomization arm: total mastectomy without radiotherapy. The B-06 trial (1976-1984) randomized patients between those undergoing total mastectomy versus lumpectomy versus those undergoing lumpectomy and breast irradiation, with all patients undergoing an axillary lymph node dissection. The records of all patients who developed a recurrence in the lung or a new primary lung tumor were reviewed to determine the incidence and laterality of confirmed and probable primary lung carcinoma. RESULTS: For the 1665 evaluable patients on the NSABP B-04 trial (mean follow-up of 21.4 years), there was a total of 23 subsequent confirmed and probable ipsilateral or contralateral primary lung carcinomas. In those patients who had received comprehensive postmastectomy radiotherapy, there was a statistically significant increase in the incidence of these new primary tumors (P = 0.029). With regard to the development of confirmed new primary ipsilateral lung carcinoma alone, the incidence was statistically significantly increased (P = 0.013) in those patients who had received radiotherapy as part of their treatment, and when confirmed and probable ipsilateral lung carcinomas were analyzed, there was a strong trend toward a statistically significant increase in those patients who had received radiotherapy (P = 0.066). For the 1850 evaluable patients on the NSABP trial B-06 (mean follow-up of 19.0 years), there was a total of 30 second primary lung carcinomas but no increase in either ipsilateral or contralateral primary tumors of the lung in those patients who had received radiotherapy. CONCLUSIONS: Extensive postmastectomy irradiation of the chest wall and regional lymphatic node areas, with consequent exposure of a greater volume of lung to higher doses as administered in the NSABP B-04 trial compared with postlumpectomy breast irradiation in the NSABP B-06 trial, was associated with an increased incidence of subsequent primary lung tumors, both ipsilateral and contralateral.