Multiple variants of the human lymphocyte homing receptor CD44 generated by insertions at a single site in the extracellular domain

The human CD44 cell-surface glycoprotein participates in a wide variety of cell-cell interactions including lymphocyte homing and tumor metastasis. The CD44 antigen is known to display extensive size heterogeneity when compared between different tissue sources although the structural basis for this variation is not yet clear. Recently, two further isotypes in addition to the basic hemopoietic form of the CD44 antigen have been cloned and sequenced and these have been found to contain all or part of a 200-400-base pair insert within the extracellular domain, suggesting that the characteristic heterogeneity in the molecule may be generated by a mechanism of alternative splicing. We have obtained further evidence for alternative splicing, and we report here the cloning and sequencing of six different CD44 sequence variants from a variety of cell lines using a combination of expression cloning and the polymerase chain reaction. Comparison of these variants indicates that each is probably assembled by the insertion of five different exon units in tandem into a discrete site within the membrane proximal region of the extracellular domain. One of the variants contains an exon that shares extensive amino acid sequence homology with a recently described rat CD44 variant that mediates tumor metastasis. Another variant contains a new exon that encodes a tandem repeat of the consensus sequence SG for covalent modification with chondroitin sulfate and is expressed predominantly on mammary tumors. We suggest that a mechanism of alternative exon splicing generates much of the observed structural heterogeneity of CD44 and that the particular set of CD44 variants expressed in a single cell may represent a precise postal code directing the final destination of migrating cells and metastatic tumors.

Chronic testicular pain following vasectomy

The incidence of chronic testicular pain following vasectomy has not been previously assessed. We have carried out a survey by postal questionnaire and telephone interview of 172 patients 4 years after vasectomy to assess the incidence of chronic testicular pain. Significant early post-operative complications occurred in 6 patients (3.5%): 2 infection, 3 haematoma and 1 orchitis. Chronic testicular discomfort was present in 56 patients (33%), considered by 26 (15%) to be troublesome but not by the other 30 (17%). Testicular discomfort related to sexual intercourse occurred in 9 cases (5%). Of the 9 patients who had sought further medical help only 2 had had further surgery (1 an epididymectomy and 1 excision of a hydrocele). Only 3 patients regretted having had the vasectomy because of chronic pain. On ultrasound examination, epididymal cysts were a common finding on both asymptomatic and symptomatic patients following vasectomy. Prior to vasectomy, all patients should be counselled with regard to the risk of chronic testicular pain.

Task versus component consistency in the development of automatic processing: a psychophysiological assessment

A study was conducted to examine the role of consistency in the development of automatic processing. Subjects performed a memory search task in which consistent and inconsistent attending and responding were factorially combined. The task was performed with memory set sizes of two and four items. Results indicated that automaticity developed with consistent attending regardless of whether responding was consistent or inconsistent. However, measures of reaction time, P300 latency, and P300 amplitude revealed costs for inconsistent responding that were attributed to both stimulus evaluation and response related processes. The results suggest that total task consistency is not necessary for the development of automatic processing. Instead, it appears that automaticity can develop for consistent task components even when stimulus-response consistency is not maintained across the entire task.

Development and transfer of automatic processing

Two studies were performed to examine the role of consistency in the development and transfer of automatic processing. Ss performed a rule-based memory search task in which they compared multidimensional probes to 1, 2, or 3 memory set rules. Results indicated that learning occurred in the absence of consistency at lower levels of task description (e.g., mapping of individual task components to responses) as long as higher level consistencies existed in the task (e.g., consistent) mapping of task components to a conceptual framework). However, the asymptotic level of this learning was modulated by the consistency with which conjunctions of task components were mapped to decisions. High positive transfer was obtained despite replacement of the exemplars of the memory set rules, suggesting that learning was not specific to the items encountered during training. On the other hand, the magnitude of positive transfer was reduced when the rules were replaced, suggesting that most of the learning took place at the level of specific rules. Some evidence was also obtained for more general process-based learning. Results are discussed in terms of their implications for models of learning and transfer.

Development and transfer of automatic processing

Two studies were performed to examine the role of consistency in the development and transfer of automatic processing. Ss performed a rule-based memory search task in which they compared multidimensional probes to 1, 2, or 3 memory set rules. Results indicated that learning occurred in the absence of consistency at lower levels of task description (e.g., mapping of individual task components to responses) as long as higher level consistencies existed in the task (e.g., consistent) mapping of task components to a conceptual framework). However, the asymptotic level of this learning was modulated by the consistency with which conjunctions of task components were mapped to decisions. High positive transfer was obtained despite replacement of the exemplars of the memory set rules, suggesting that learning was not specific to the items encountered during training. On the other hand, the magnitude of positive transfer was reduced when the rules were replaced, suggesting that most of the learning took place at the level of specific rules. Some evidence was also obtained for more general process-based learning. Results are discussed in terms of their implications for models of learning and transfer.

Antibodies to Epstein-Barr viral antigens in familial rheumatoid arthritis

Serum antibodies to Epstein-Barr virus (EBV) were measured in members of twenty-nine families in which two or more first degree relatives had rheumatoid arthritis (RA). These patients were assessed clinically for activity of disease and their treatment recorded. A higher proportion of seropositive individuals was found among patients and affected kindred than among the non-affected groups. Antibody titres to Viral Capsid Antigen (VCA) tended to be higher in patients and affected kindred. In those individuals in whom antibody to Early Antigen (EA) was present there was a lower titre of antibody to Epstein-Barr Nuclear Antigen (ENBA). The results suggest that an immunoregulatory defect may exist in some patients with RA which allows for enhanced expression of EBV.

Bone marrow transplantation for acute non-lymphocytic leukemia: a report from the Childrens Cancer Study Group of sixty-seven children transplanted in first remission

Sixty-seven children with acute non-lymphocytic leukemia (ANLL) in first remission underwent HLA-identical sibling bone marrow transplants as part of a cooperative study by the Childrens Cancer Study Group. Three patients died of sepsis before marrow recovery. Sixty-four patients recovered marrow function and have been followed for a median of greater than 1300 days. Two-year actuarial survival is 59% (95% confidence interval (CI): 47-71%). The risk of relapse by 2 years is 16% (95% CI: 6-26). All relapses occurred among patients with single-dose irradiation (p = 0.07), but these patients also experienced a diminished risk of acute graft-versus-host disease (AGVHD) (p = 0.12) compared to patients conditioned with fractionated irradiation. Radiation technique (single-dose vs fractionated) did not affect survival or the risk of development of interstitial pneumonia. Significant AGVHD (greater than or equal to grade II) occurred in 27 patients (40%). Patients with AGVHD were at increased risk of death due to sepsis or interstitial pneumonia during the first year after transplant, but disease-free survival was unaffected by AGVHD, because all 10 relapses occurred in patients without significant AGVHD. Neither survival nor relapse risk were affected by patient age, sex, white cell count at diagnosis, or FAB classification. This collaborative transplant study has resulted in survival data comparable to those of single institutions and the best reported outcomes of conventional chemotherapy.

Childhood leukemia and parents' occupational and home exposures

A case-control study of children of ages 10 years and under in Los Angeles County was conducted to investigate the causes of leukemia. The mothers and fathers of acute leukemia cases and their individually matched controls were interviewed regarding specific occupational and home exposures as well as other potential risk factors associated with leukemia. Analysis of the information from the 123 matched pairs showed an increased risk of leukemia for children whose fathers had occupational exposure after the birth of the child to chlorinated solvents [odds ratio (OR) = 3.5, P = .01], spray paint (OR = 2.0, P = .02), dyes or pigments (OR = 4.5, P = .03), methyl ethyl ketone (CAS: 78-93-3; OR = 3.0, P = .05), and cutting oil (OR = 1.7, P = .05) or whose fathers were exposed during the mother's pregnancy with the child to spray paint (OR = 2.2, P = .03). For all of these, the risk associated with frequent use was greater than for infrequent use. There was an increased risk of leukemia for the child if the father worked in industries manufacturing transportation equipment (mostly aircraft) (OR = 2.5, P = .03) or machinery (OR = 3.0, P = .02). An increased risk was found for children whose parents used pesticides in the home (OR = 3.8, P = .004) or garden (OR = 6.5, P = .007) or who burned incense in the home (OR = 2.7, P = .007). The risk was greater for frequent use. Risk of leukemia was related to mothers' employment in personal service industries (OR = 2.7, P = .04) but not to specified occupational exposures. Risk related to fathers' exposure to chlorinated solvents, employment in the transportation equipment-manufacturing industry, and parents' exposure to household or garden pesticides and incense remains statistically significant after adjusting for the other significant findings.

Magnetic resonance imaging in hydatid disease

Magnetic resonance imaging was evaluated in 12 patients with hydatid disease (Echinococcus granulosus). Patients also underwent real time ultrasound and computed tomography imaging. Clear images of hepatic hydatid cysts were produced by magnetic resonance imaging, and intracyst structures were demonstrated. Changes in the appearance of cysts were seen following chemotherapy. Whilst not cost effective at present, if further improvements allow differentiation of simple (epithelial) and hydatid cysts or viable and dead hydatid cysts this technique could be of clinical value.

Magnetic resonance imaging--its application to cervical carcinoma

Twenty-five women with primary carcinoma of the cervix were examined with magnetic resonance imaging (MRI). A number of different pulse sequences with T1 and T2 weighting were employed to determine optimum tissue contrast, and the potential for staging cervical cancer was assessed and compared with the clinical findings. MRI is seen to give a unique view of cervical cancer in particular in stage I and II disease where other imaging techniques have known limitations. In addition, stages III and IV were well seen with demonstration of tumour comparable with that of computerized axial tomography (CT).

The changes in the intervertebral disc after chemonucleolysis demonstrated by magnetic resonance imaging

Magnetic resonance imaging (MRI) of the spine produces images which reflect the chemical composition of the intervertebral disc. We have conducted a prospective study of the serial changes in the MRI appearance of the intervertebral disc after chemonucleolysis with the enzyme chymopapain. Fourteen patients were studied after single-level chemonucleolysis and the results compared with a control group of 17 discs in six patients who had diagnostic discography without enzyme insertion. A consistent pattern of gradual loss of signal from the nucleus pulposus culminating in complete loss of nuclear signal was seen in all cases after chemonucleolysis. Chymopapain therefore produced MRI changes analogous with premature gross disc degeneration. The rate at which this occurred varied; complete loss of signal took at least six weeks. Transitory minor end-plate changes were present in five patients, probably representing a mild chemical discitis. No similar changes were seen in the discography group.

Magnetic resonance imaging and hydatidiform mole

Five women with complete and partial hydatidiform mole were examined by magnetic resonance imaging (MRI). Spin-echo pulse sequences (T2 weighted) were found to provide excellent resolution, while inversion-recovery pulse sequences (T1 weighted) gave better pathological detail. The myometrium was clearly seen on each patient and no invasion by the tumour detected. This corresponded to the histological findings. The potential uses of magnetic resonance in the diagnosis of primary and recurrent trophoblastic disease and its role in management are discussed.

Identifying a limited number of foods important in supplying selected dietary nutrients

Three methods were developed to identify a limited number of foods that are important dietary contributors of fat, dietary fiber, and vitamins A, C, and E. In the first method, foods were ranked by the amount of each nutrient supplied per person per day and the effect each food had on the relative ranking of individuals with respect to the intake of those nutrients. Foods scoring high on both scales for a given nutrient were selected as important dietary contributors of that nutrient. In the second method, foods were selected according to the mean nutrient contribution per consumer (nonconsumers of a food were eliminated from this estimation procedure). In the third method, foods were selected that contributed a relatively large percentage of the total dietary intake of a given nutrient. The three methods were applied to data from an extensive dietary questionnaire. The authors then compared the limited lists of foods identified by each method. Generally, the methods yielded similar food lists. Regression analysis was then employed to test the ability of the selected foods to predict the nutrient totals calculated from the original, more extensive dietary questionnaire. The results suggest that a limited number of foods may have strong predictive ability, but that has not been tested in any other population.

Magnetic resonance imaging and discography in the diagnosis of disc degeneration. A comparative study of 50 discs

The lumbar spines of 22 patients were examined for disc degeneration by magnetic resonance imaging (MRI) and by discography. The results from 50 intervertebral discs visualised by both techniques were independently assessed and graded on a five-point scale from normality to gross degeneration and then compared. In 44 discs the results agreed. Of the six discs which gave differing results, four discrepancies were due to observer error and two to incorrect placement of the discographic needle. MRI was shown to be more accurate than discography in the diagnosis of disc degeneration. It has several major advantages, which should make it the investigation of choice.

Pre-operative magnetic resonance imaging of stage 1 endometrial adenocarcinoma

Twelve women with stage I endometrial adenocarcinoma were examined by magnetic resonance imaging before definitive surgery. Using this technique the depth of myometrical invasion, tumour site and cervical involvement were assessed and the results compared with the operative and pathological findings. Magnetic resonance imaging is a unique non-invasive method of assessing the early stages of endometrial adenocarcinoma before radiotherapy and surgery.

Magnetic resonance imaging and placenta previa

Twenty-five women with diagnoses of placenta previa on ultrasound examination underwent magnetic resonance imaging examination. An assessment of placental position and the relationship of the lower placental edge to the internal os was made with both techniques and the results were compared. There was complete correlation of placental localization but significant differences were found in the determination of the degree of placenta previa. This occurred more often with posteriorly situated placentas. Magnetic resonance imaging directly affected management with regard to delivery in seven cases. Magnetic resonance imaging provides a technique capable of accurately assessing placental position and its relationship to the cervix, thereby leading to a reduction in hospitalization and inappropriate operations.

Effects of norepinephrine on the dog common carotid, coronary and renal arteries: in vitro studies

The effects of norepinephrine were studied on segments of the common carotid, left circumflex and renal arteries of dogs with the endothelium intact and removed. Norepinephrine induced a dose-dependent increase in tension in segments of the renal and carotid artery but did not produce any effect on the coronary artery. Although the absence of endothelium did not affect the magnitude of the norepinephrine-induced vasoconstriction of the renal artery, it elicited a more pronounced response in the carotid artery in which the endothelium was removed. Our data suggest that the vascular response to norepinephrine is dependent upon the specific arterial bed and, secondly, that the endothelium plays a determinant role in the magnitude of the response of the carotid artery.