Spacing of cytochrome oxidase blobs in visual cortex of normal and strabismic monkeys

Some models of visual cortical development are based on the assumption that the tangential organization of V1 is not determined prior to visual experience. In these models, correlated binocular activity is a key element in the formation of visual cortical columns, and when the degree of interocular correlation is reduced the models predict an increase in column spacing. To examine this prediction we measured the spacing of columns, as defined by cytochrome oxidase (CO) blobs, in the visual cortex of monkeys whose binocular vision was either normal or disrupted by a strabismus. The spatial distribution of blobs was examined in seven normal and five strabismic macaques. Tangential sections through the upper layers of the visual cortex were stained to reveal the two-dimensional (2D) pattern of CO blobs. Each blob was localized and their center-to-center spacing, packing arrangement and density were calculated using 2D nearest-neighbor spatial analyses. The mean center-to-center spacing of blobs (590 microm for normally reared and 598 microm for strabismic macaques) and the mean density of blobs (3.67 blobs/mm2 for normally reared and 3.45 blobs/mm2 for strabismic macaques) were not significantly different. In addition, the 2D packing arrangement of the blobs was not affected by strabismus. While it is clear that neural activity plays a key role in the elaboration and refinement of ocular dominance cortical modules, we conclude that it does not determine the spatial period of the pattern of CO blobs. This suggests that aspects of the neural circuitry underlying the columnar architecture of the visual cortex are established prenatally and its fundamental periodicity is not modifiable by experience.      

Pancreas divisum: thin-section CT

Twelve patients with known pancreas divisum underwent thin-section computed tomography (CT) to determine the capability of CT to depict this pancreatic anomaly. Focal pancreatic enlargement was present in five patients. Two distinct pancreatic moieties separated by a fat cleft were noted in three patients; a fourth patient had focal atrophy in the distribution of the dorsal pancreas. The two pancreatic moieties were identified at the same craniocaudal level in all four of these patients. The dorsal duct was depicted in all 12 patients, while the short ventral duct was seen in only five of the 12 patients. Failure of the ventral and dorsal pancreatic ducts to fuse was identified in all five patients in whom both ducts were seen. CT may not enable specific diagnosis of pancreas divisum in the majority of patients. If, however, distinct pancreatic moieties or unfused ductal systems are evident, the diagnosis may be confidently suggested.     

Diphenylhydantoin-induced pure red cell aplasia

The pathogenesis of diphenylhydantoin-induced pure red cell aplasia was investigated in the case of a 32-year-old man who developed pure red cell aplasia while he was under treatment with diphenylhydantoin. The patient's serum IgG purified from serum drawn at the time of diagnosis suppressed normal allogeneic marrow colony-forming (CFU-E) and burst- forming (BFU-E) and autologous blood BFU-E growth in vitro only in the presence of diphenylhydantoin. This IgG-diphenylhydantoin complex had no effect on CFU-GM growth in vitro. Normal IgG or patient's IgG purified from serum drawn after the remission of red cell aplasia had no effect on erythroid colony formation in vitro in the presence of diphenylhydantoin. The IgG-diphenylhydantoin complex exerted no direct cytotoxic effect on normal marrow erythroblasts, CFU-E, and BFU-E, nor did it interfere with the action of erythropoietin on marrow erythroblasts. These studies suggest that diphenylhydantoin-induced red cell aplasia is immunologically mediated through an IgG inhibitor, which requires the presence of the drug to suppress erythroid colony formation in vitro. This inhibitor seems to exert its effect on erythroid progenitors at or beyond the stage of differentiation of CFU- E, but not on erythroblasts.     

Combination “Sandwich” Therapy for Extensive Renal Calculi in 100 Consecutive Patients: Immediate, Long-Term and Stratified Results from a 10-Year Experience

Purpose

We determined the immediate and long-term efficacy of combination “sandwich” therapy for management of large, extensively branched calculi in 100 consecutively treated patients.

Materials and Methods

We treated 61 women and 39 men for stones ranging from 2.2 to 66 cm.² (mean 20.8) with percutaneous debulking followed by shock wave lithotripsy and, when necessary, secondary nephroscopy via the mature tract. The primary debulking was performed via 1 to 3 tracts (total 106, mean 1.06 per patient), following which 1 to 3 shock wave treatments (total 127, mean 1.3 per patient) were administered. Subsequently, 62 patients underwent 71 secondary or tertiary percutaneous procedures (mean 1.1 per patient).

Results

Total hospital stay ranged from 3 to 44 nights (mean 12.2) and decreased with experience. In 34 patients 40 complications developed, the most frequent of which were bleeding requiring transfusion in 14 patients and fever or sepsis delaying a planned procedure or hospital discharge in 20 patients. For patients with struvite stones the transfusion rate and fever/sepsis rate was 20 and 33%, respectively, compared to only 10 and 12%, respectively, for those patients with noninfection related stones. Of 87 patients available for 1-month radiographic followup 55 (63%) were stone-free, while 32 (37%) had discrete residual gravel. With time and experience, the stone-free rate improved from 52 to 70%. Of 55 patients followed for a mean of 40.5 months ipsilateral stones recurred in 13 (22.8%). Of 39 patients with struvite calculi 11 (28%) had recurrent bacteriuria or infection. Renal function, defined by serum creatinine, ranged from 0.6 to 3.9 mg./dl. (mean 1.3) before treatment and from 0.5 to 6.4 mg./dl. (mean 1.4) 1 to 101 months (mean 31) after treatment.

Conclusions

This combined sandwich approach offers immediate and long-term results comparable to other forms of management currently available for these challenging cases. Furthermore, this approach may be applied successfully to virtually any patient with large, extensively branched or otherwise complex stones.