Biomedical subjects
L Mack
Publications and source records attributed to L Mack.
Healthy mom, healthy baby: pregnancy and prenatal issues.
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Relationship of a new histological categorization of ductal carcinoma in situ of the breast with size and the immunohistochemical expression of p53, c-erb B2, bcl-2, and ki-67.
Ductal carcinoma in situ (DCIS) represents a heterogeneous group of diseases. There is no generally accepted classification for the different cytological and architectural types of DCIS. A recent study (Scott et al, 1995) indicates that over 90% of DCIS can be easily classified into the following five categories: high grade (HG), intermediate grade (IG), low grade (LG), pure micropapillary (M), and pure apocrine (A). The aim of this study was to determine if there is a relationship between lesion size and the immunohistochemical expression of p53, c-erb B2, bcl-2, and ki67 with this reproducible categorization of DCIS. Seventy cases of DCIS diagnosed between 1984 and 1995 were obtained from the Departments of Pathology at two teaching hospitals in London, Ontario. The original sections were reviewed, classified according to Scott et al (1995), and representative sections were cut for immunohistochemical (IHC) studies. IHC stains were scored using a previously described semiquantitative scoring system (Allred et al, 1993). Size was taken from the gross measurement if the lesion was palpable or recorded as the largest dimension, as measured on the histological slide, for nonpalpable cases. Of the 70 DCIS cases, 17 (24.3%) were HG, 23 (32.9%) were IG, 21 (30%) were LG, seven (10%) were pure micropapillary cases, and two (2.9%) were pure apocrine DCIS. The mean size of the DCIS for each subcategory was statistically significantly different (P = .008). In particular, the micropapillary DCIS cases were largest (mean size, 17 mm). The mean immunohistochemical scores for c-erb B2 for each category were also statistically different (P = .007), whereas the mean scores for p53 and ki67 for each category trended toward significance (P = .073, P = .062, respectively). There were no significant differences between bcl-2 mean scores and each subcategory. Size of DCIS and c-erb B2 positivity are known to be associated with more aggressive clinical behavior and more advanced histologic features, respectively. Because this combined histological cytological classification system is predictive of size and c-erb B2 positivity, our results support the clinical relevance of this classification system.
Prenatal diagnosis of Beckwith-Wiedemann syndrome.
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Hemispheric specialization for handwriting in right handers.
Hand preference may be related to either lateralized language, movement representations, or both. Anatomic and behavioral studies have revealed that whereas each hemisphere has motor control of the contralateral distal and proximal limb movements, this same hemisphere's control over the ipsilateral limb is limited to proximal movements. This differential proximal-versus-distal organization may have functional implications such that when right handers write with their left hand they must be use more proximal musculature than when they write with their right hand. If hand preference is related to lateralized movement representations, right handers may also use more proximal than distal movements when drawing with their left than with their right hand. If one uses distal musculature to write or draw, the elbow travels through space less than if one uses proximal musculature. We studied 12 right handers by having them write and draw with their right and left hands and measured the spatial amplitude of their elbow movements. We found that when writing or drawing, right handers moved their left elbow more than their right. These results suggest that it is the lateralized movement representations that may be primarily responsible for writing hand preference.
Duplication (6q) syndrome diagnosed in utero.
We report on a case of partial duplication 6q detected ultrasonographically. The clinical picture noted in utero is consistent with the adult phenotype previously reported in the literature.
Preliminary evaluation of color Doppler imaging for investigation of intrascrotal pathology.
Color Doppler ultrasound facilitates investigation of blood flow in addition to imaging parenchymal abnormalities. To assess the clinical use of this technique we evaluated 25 consecutive patients with indications for intrascrotal imaging. Color flow imaging added useful information in all 11 patients evaluated for chronic scrotal pain and in 6 of 7 evaluated for acute scrotal pain. In contrast, color flow ultrasound provided little additional information in 7 patients with intrascrotal masses. Color flow ultrasound imaging is a promising method that may prove to be useful for assessment of selected patients with intrascrotal pathological conditions.
Survival of Borrelia burgdorferi in human blood stored under blood banking conditions.
Hematogenous dissemination of organisms occurs in many spirochetal diseases, including Lyme disease and syphilis. Although syphilis has been transmitted by transfusion, in the vast majority of cases, only fresh blood products were involved, in part because Treponema pallidum survives poorly when refrigerated in citrated blood. Because of the rising incidence of Lyme disease in certain areas, whether its causative agent, Borrelia burgdorferi, could survive under blood banking conditions was studied. Dilutions of stock cultures of two strains of B. burgdorferi were inoculated into samples of citrated red cells (RBCs). Viable spirochetes were recovered from RBCs inoculated with 10(6) organisms per mL, after refrigeration for as long as 6 weeks. It is concluded that B. burgdorferi may survive storage under blood banking conditions and that transfusion-related Lyme disease is theoretically possible.
Three-dimensional computergraphic analysis of apraxia. Neural representations of learned movement.
The left cerebral hemisphere in man contains anatomical structures specialized not only for language but also for higher-order motor programming. One method of studying the nature of these motor programs is by observing the type of errors made by patients who have left hemisphere damage. A major problem, however, in investigating the disorders that result from failure of this specialized left hemisphere system (the apraxias) has been the difficulty in obtaining objective measurement of movement in three-dimensional space. To this end, we provide the first three-dimensional analysis of the nature of movement errors in apraxia. Two apraxic subjects with lesions to the left hemisphere and 5 matched control subjects were studied. The apraxic subjects showed impairments in the control of movement timing and spatial relations, as well as decoupling in the normally tight relation between certain spatial and temporal aspects of their movement trajectories. Further, the use of the distal musculature by apraxic subjects was more impaired than their use of the proximal musculature, suggesting more distal representation in any space-time maps of learned movement. These data provide further insight into the nature of the representations of learned skilled movements in the left cerebral hemisphere.
Blood contamination of medical records.
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A comparison of lexical-semantic impairments in left hemisphere stroke and Alzheimer's disease.
Patients with aphasia due to left hemisphere stroke and patients with Alzheimer's disease, who were matched for severity of naming impairment, were compared on tests of lexical-semantic processing. The results suggest that the lexical-semantic impairments in both groups are due to a combination of impaired access to, and loss of, lexical-semantic information, but that impaired access is more prominent in stroke patients, whereas Alzheimer's disease patients suffer a greater loss of information. The results are discussed in terms of a brain model of the storage and processing of lexical-semantic information, and with respect to implications for treatment strategies.
Lack of effect of oral acyclovir on prevention of aphthous stomatitis.
Aphthous stomatitis (canker sores) is a common cause of recurrent mouth ulceration. The effect of long-term oral acyclovir therapy on aphthous stomatitis recurrences was evaluated in 44 patients who were in a double-blind treatment trial for recurrent genital Herpes simplex infections. Twenty-five subjects received oral acyclovir daily for one year, while 19 received the drug only during outbreaks of herpes. The number of patients who experienced recurrences of aphthous stomatitis and the frequency and duration of attacks per patient were not significantly different between groups. Furthermore, no consistent change in attack rate was observed in members of either group compared to that reported before they had entered the trial. We conclude that oral acyclovir is not effective for prevention of recurrent aphthous stomatitis in most patients.
Transitive movements in a deafferented man.
It has not been determined if the performance of transitive movement requires sensory feedback from the limb to the brain. We tested a deafferented patient's ability to pantomime, imitate, and use actual objects in both eyes open and eyes closed conditions. Although his performance deteriorated when his eyes were closed, the major error made by this patient was the inability to correctly orient the instrument (or pretended instrument) toward the object of the instrument's action.
Apraxia after a superior parietal lesion.
We studied a patient who had unilateral (left) limb apraxia associated with a lesion of her right superior (Brodmann areas 5 and 7) and inferior parietal lobes. In monkeys areas 5 and 7 contain "hand-manipulation neurons" that are thought to be important in proprioceptive guidance. Therefore, we tested our patient with her eyes open and closed. Her left hand performance with pantonime, imitation, and use of actual objects dramatically deteriorated in the absence of visual guidance. In addition, although the patient did not have optic ataxia and had normal proprioception, she had difficulty using her left forelimb in tasks that require transcoding from a visual to a somatesthetic spatial coordinate system. We propose that each superior parietal lobe is not only responsible for transcoding from a visual-spatial code into a somatesthetic-spatial code but is also critical for transcoding spatial-temporal representations of skilled movement into a somatesthetic-spatial code.
Recombination aneusomy of chromosome 5 associated with multiple severe congenital malformations.
A male infant is described in whom congenital anomalies were recognized prenatally by ultrasound examination. The infant was delivered following spontaneous labor and died approximately 15 min after birth. An autopsy revealed major anomalies in the central nervous system (holoprosencephaly with premaxillary agenesis), the gastrointestinal system (esophageal atresia) and the heart (tetralogy of Fallot). Chromosomal studies revealed recombinant chromosome 5 [46,XY, rec(5), dup q, inv(5)(p15q32)], resulting in partial trisomy 5q and partial monosomy 5p. Cytogenetic investigation of the family revealed a pericentric inversion of chromosome 5 in the father and paternal grandmother, 46,XY (and XX, respectively,) inv(5)(p15q32). The congenital anomalies in this infant are more extensive and severe than previously reported in cases of recombination aneusomy involving chromosome 5.
Pantomime agnosia.
Visual agnosia is impaired visual recognition not explained by defective visual acuity, visual fields, attention, or general mental ability. Two nonapraxic patients with lesions in the left occipital lobe could imitate pantomimes they could not recognise. Although both patients had a hemianopia, sparing of gesture imitation shows that no visual defect accounts for their inability to recognise pantomimes. Both patients were amnestic and alexic but had no general impairment of cognitive ability to account for a pantomime-recognition disorder. These patients seem to have agnosia for pantomime. From the computed tomograms from these patients, we propose that inferior visual association cortex is critical for gesture comprehension, whereas superior portions of these structures are critical for imitating or performing pantomime to an object presented visually.
Multicystic dysplastic kidney: observations of contralateral disease in the fetal population.
To evaluate multicystic dysplastic kidney (MDK) and associated contralateral renal abnormalities in the fetal population, 27 cases detected and followed in utero were reviewed retrospectively. The sonographic assessment included estimation of amniotic fluid volume and interval growth, evaluation for non-genitourinary anomalies, and postnatal follow-up study. Contralateral renal anomalies were detected in 41% of the fetuses and included obstruction of the ureteropelvic junction, renal agenesis, renal hypoplasia, and bilateral MDK. The incidences of these malformations were compared with results of earlier studies of MDK in the pediatric and adult populations. Lethal anomalies, such as bilateral MDK and MDK associated with contralateral agenesis, are common (19% and 11%, respectively) in the fetal population; obstruction of the contralateral ureteropelvic junction, a nonlethal anomaly, was seen less commonly (7%). Perinatal death from lethal abnormalities may spuriously raise the incidence of nonlethal contralateral abnormalities in the pediatric and adult populations. Contralateral mild fetal pyelectasis, found in 15% of fetuses with MDK, was not clinically significant.
Ultrasound and the intestinal wall: experimental methods.
High-frequency, high-resolution ultrasound provides a new approach to imaging structures in the wall of the gastrointestinal tract. Questions about internal ultrasound include: is the ultrasound image specific for disease states, in which diseases will this technology add new and useful information not available from existing diagnostic studies, and what are the necessary characteristics for a system to accomplish these diagnoses? Answering these questions requires that precise correlations be made between the ultrasound image and pathology. We have developed a method to image a resected gastrointestinal tissue with ultrasound and to remove and examine the corresponding piece of tissue histologically. Changes in wall thickness, obliteration of layers, and changes in the characteristics of the tissue can be studied. We have shown that ultrasound can resolve the layers of the gut wall. This system should enable us to answer questions about which intestinal wall diseases are suitable for internal ultrasound imaging and characterize the engineering features of an optimal ultrasound system for clinical application.