Evidence that the earliest generated cells of the murine cerebral cortex form a transient population in the subplate and marginal zone.

We used bromodeoxyuridine to label the earliest generated cells of the murine cerebral cortex while they were dividing, and then observed their distributions at several instances later in development. Shortly before birth, many of the labelled cells were either above the cortical plate, in the marginal zone, or below it, in the region known as the subplate in other species. These cells had disappeared by postnatal day 21.     

Measurement of diet in a large national survey: comparison of computerized and manual coding of records in household measures

A diary method using household measures was employed to obtain dietary records in a large national prospective survey and a computer program, DIDO (Diet In Data Out), was designed for direct entry of the diaries. The accuracy of this computerized coding system was examined alongside that of the manual coding used for a similar diary in a previous wave, 7 years earlier, of the same survey. Accuracy was assessed by analysis of the errors in the coded and checked records by stringent re-checking of nominal 2% random subsamples of the diet diaries coded by each method. The mean time to code and check each of the 2086 7-day records in the whole survey using DIDO was 58 minutes (SD 30) compared with reported results of 1–4 hours for manual methods. The mean error rate of computerized coding and checking with DIDO was 2.3% (SD 2.1; range 0–8.9) per diary in the subsample. Correcting these mistakes made insignificant changes to the calculated mean energy and nutrient intakes for the subsample. The percentage of individuals changing to an adjacent third of nutrient distribution after correcting unambiguous errors ranged from none (for alcohol) to 11% (for carbohydrate and calcium intake). The mean error rate on a similar subsample of diaries from the earlier survey which had been coded manually was significantly higher at 5.9% (SD 4.1; range 0–17) per diary. Emphasis is laid on the importance, in coding, of dealing with ambiguities in the subjects' records, since this can affect the accuracy and the precision of the nutrient results obtained. We conclude that the DIDO coding method has the advantages of greater accuracy, speed, consistency and efficient data handling, and affords greater data accessibility for checking, compared with manual systems.     

Body fat in identical twins reared apart: Roles for genes and environment

We report analyses of data on body fat from a cohort of 34 separated monozygotic twin pairs (MZA) and a matched sample of 38 pairs of monozygotic twins reared together (MZT) originally studied by James Shields. The correlation for MZA pairs was. 61 and the correlation for MZT pairs was. 75. These correlations did not differ significantly, nor did correlations differ between MZA pairs subclassified as having been raised in relatively more or less similar environments. Our results suggest important roles for both genes and environment in the accumulation of body fat and support other adoption studies in suggesting that adult environments rather than rearing environments are the most important nongenetic determinants of levels of body fat in adults.Supported by National Institute of Mental Health Grant MH43409 to R.A.P. and a Grant in Aid from the Dight Institute of Human Genetics to I.I.G.     

Hypothermia differentially affects tuning curves generated by forward and by simultaneous masking.

In the gerbil maintained at euthermic (37.5 degrees C) conditions, forward masking produces a compound action potential tuning curve (CAP TC) which is less sensitive but more sharply tuned than that which is generated by simultaneous masking. These differences between forward- and simultaneously-masked CAP TCs are minimized at hypothermic (30 degrees C) conditions. The unmasking effect occurs at both temperatures, suggesting that hypothermia does not exert these changes by eliminating two-tone suppression.     

In vitro platelet aggregability studies: lack of evidence for platelet hyperactivity in systemic sclerosis.

Systemic sclerosis is characterised by vascular endothelial damage. Platelets adhering to the exposed subendothelium may contribute to the inflammatory changes found in the vessel wall. Increased in vitro platelet aggregability in systemic sclerosis has been reported. In vitro platelet aggregation of platelet rich plasma obtained from patients with systemic sclerosis (CREST (calcinosis, Raynaud's phenomenon oesophageal dysmotility, sclerodactyly, telangiectasia) variant) and from controls matched for age and sex was compared. Collagen, ADP, and platelet activating factor were used as aggregating agents. The actions of a platelet activating factor antagonist, BN52063, were also examined. Each agonist caused dose dependent platelet aggregation; there was no difference in either rate of primary aggregation or maximum percentage aggregation between platelets derived from patients with systemic sclerosis and from the control group (analysis of variance). BN52063 was shown to be a dose dependent, competitive antagonist of platelet aggregation induced by platelet activating factor; there was no difference in its action on platelets derived from patients with systemic sclerosis or controls. These results do not support the hypothesis that platelets from patients with systemic sclerosis are hyperactive and may explain the disappointing results obtained with antiplatelet drugs in systemic sclerosis.     

Assessment of clinical renal preservation by phosphorus-31 magnetic resonance spectroscopy

To evaluate the role of magnetic resonance spectroscopy (MRS) and to develop surface coils for assessing cadaveric renal viability during hypothermic storage, we used the monophosphate/inorganic phosphate ratio (MP/Pi) to monitor phosphorous metabolites in intact kidneys during various renal preservation maneuvers. Eighteen canine kidneys and 16 cadaveric kidneys were studied as follows: Group 1 (N = 4) in situ kidneys were monitored by implanted MRS coils; Group 1 (N = 4) ex vivo kidneys were immediately attached to vascular cannulas and monitored by MRS surface coils during normothermic perfusion; Group 3 (N = 4) kidneys were removed, cold-flushed and, after 24 hours of 4C storage, monitored by MRS surface coils before and during four hours of reperfusion via vascular cannulas; Group 4 (N = 6) kidneys were removed, cold-flushed and monitored by surface coils during cold storage up to 72 hours. In addition, 16 cadaveric kidneys were studied while in sterile cold-storage containers. Postoperative renal function was followed in recipient patients. The MP/Pi ratios in Group 1 kidneys correlated with the ability to regenerate adenosine triphosphate (ATP). Groups 2 and 3 showed similar regeneration of ATP and MP/Pi after postischemic reperfusion, and the signal-to-noise ratios of the surface coils were better than those in the implanted coils in Group 1. Surface-coil monitoring in Group 4 kidneys showed predictable decay rates of MP/Pi during one to 72 hours of cold storage; in contrast, simultaneous cortical medullary microcirculation studies with 99mTc-macroaggregated albumin were inconclusive. Human cadaveric kidneys with high MP levels were associated with excellent renal function after transplantation, while those with low MP (less than or equal to 0.50) were associated with nonviability. We conclude that MRS is a practical and safe diagnostic modality for clinical transplantation.     

Surgical staging of gastric carcinoma: sources and consequences of error

Macroscopic 'TNM' staging was performed during 78 consecutive operations for gastric carcinoma and compared with subsequent pathological staging. Surgical assessment was correct for tumour (T) in 60 per cent when depth of invasion was assessed, for nodes (N) in 61 per cent, for liver metastases (M) in 92 per cent but for all aspects in only 21 per cent. Curability (conservatively defined as T1-3, N0-1, M0) was correct in 8 of 18 patients thus assessed at surgery and incurability was pathologically correct in 58 of 60 patients. Despite inaccurate surgical staging, no patient was denied a resection although 10 patients had unduly radical procedures for their stage and 2 had inappropriately conservative procedures for their stage (but without evidence of residual disease). Staging errors did not jeopardize conventional surgical management substantially and use of intra-operative microscopic sampling of nodes would have improved surgical treatment only minimally.     

Nodal involvement in poorly differentiated breast cancer.

The degree of nodal involvement in a consecutive series of 400 patients with invasive ductal breast cancer is presented. A positive correlation was observed between the number of metastatic nodes identified and the number of axillary nodes examined for poorly but not moderately differentiated tumours. The relevance of this observation to breast cancer trials is discussed.