Biomedical subjects

K M Murphy

Publications and source records attributed to K M Murphy.

150 records · Page 9Linked to original sources

PubMedDate not supplied

Experience-dependent development of NMDAR1 subunit expression in the lateral geniculate nucleus.

Monocular deprivation early in postnatal development leads to anatomical and physiological changes in the lateral geniculate nucleus (LGN) and visual cortex. Many of these changes are dependent upon activation of the NMDA receptor. We have examined the role of visual experience in modifying NMDAR1 subunit expression in the LGN of animals reared with various forms of visual deprivation. Following monocular deprivation initiated either at eye opening or at the peak of the critical period, there were approximately 20% fewer NMDAR1-immunopositive neurons in the deprived laminae of the LGN. The loss of NMDAR1-immunopositive neurons was found throughout both the binocular and monocular segments of the LGN and after monocular deprivation until just 3 weeks of age. These results indicate that the loss of NMDAR1 in the LGN following monocular deprivation does not simply reflect changes in the visual cortex. The loss of NMDAR1 expression was not necessarily permanent. Initiation of binocular vision at the peak of the critical period ameliorated the effect of monocular deprivation and the introduction of a period of reverse occlusion led to a complete reversal. Taken together, the results show that the expression of the NMDAR1 subunit in the LGN can be modified by the pattern of visual experience during postnatal development.

Animals↗

PubMedDate not supplied

Bilateral amblyopia after a short period of reverse occlusion in kittens.

The majority of neurones in the visual cortex of both adult cats and kittens can be excited by visual stimulation of either eye. Nevertheless, if one eye is deprived of patterned vision early in life, most cortical cells can only be activated by visual stimuli presented to the nondeprived eye and behaviourally the deprived eye is apparently useless. Although the consequences of monocular deprivation can be severe, they can in many circumstances be rapidly reversed with the early implementation of reverse occlusion which forces the use of the initially deprived eye. However, by itself reverse occlusion does not restore a normal distribution of cortical ocular dominance and only promotes visual recovery in one eye. In an effort to find a procedure that might restore good binocular vision, we have examined the effects on acuity and cortical ocular dominance of a short, but physiologically optimal period of reverse occlusion, followed by a period of binocular vision beginning at 7.5 weeks of age. Surprisingly, despite the early introduction of binocular vision, both eyes attained acuities that were only approximately 1/3 of normal acuity levels. Despite the severe bilateral amblyopia, cortical ocular dominance appeared similar to that of normal cats. This is the first demonstration of severe bilateral amblyopia following consecutive periods of monocular occlusion.

Amblyopia↗

PubMedDate not supplied

The process of restructuring and the treatment of obesity in women.

Obesity is a prevalent health behavior that is difficult to treat because of its complexity, constraints on provider time, and negligible insurer reimbursement. In this comparative case study the authors describe two obese women's weight loss and lifestyle change efforts while enrolled in a nine-month, multidisciplinary weight loss program. The researchers conducted three semistructured interviews during six months. Eight major themes were identified: (1) support networks. (2) internalization/externalization, (3) routines, (4) relapse, (5) change in perspective, (6) reward/punishment, (7) emotional issues, and (8) life balance. These themes parallel Johnson's three-stage theory of cognitive restructuring. (See Johnson, 1990, "Restructuring: An Emerging Theory on the Process of Losing Weight." Journal of Advanced Nursing, 15, 1289-1296.) Researchers reveal that complex health problems are replete with social and psychological factors that may undermine treatment success. Understanding a client's experience while attempting behavior change is crucial for the development of interventions that address difficult and costly health behaviors.

Adaptation, Psychological↗

PubMedDate not supplied

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.

Animals↗

PubMedDate not supplied

The RAI-PC: an assessment instrument for palliative care in all settings.

Large numbers of persons in most types of healthcare settings have palliative care needs that have considerable impact on their quality of life. Therefore, InterRAI, a multinational consortium of researchers, clinicians, and regulators that uses assessment systems to improve the care of elderly and disabled persons, designed a standardized assessment tool, the Resident Assessment Instrument for Palliative Care (RAI-PC). The RAI-PC can be used for both the design of individual care plans and for case mix and outcomes research. Some elements of this instrument are taken from the resident assessment instrument (RAI) mandated for use in all nursing homes in the United States and widely used throughout the world. The RAI-PC can be used alone or in counjunction with the other assessment tools designed by the InterRAI collaboration: the RAI for homecare (RAI-HC), for acute care (RAI-AC), and for mental health care (RAI-MH). The objective of this study was to field test and carry out reliability studies on the RAI-PC. After appropriate approvals were obtained, the RAI-PC instrument was field tested on 151 persons in three countries in more than five types of settings. Data obtained from 144 of these individuals were analyzed for reliability. The reliability of the instrument was very good, with about 50 percent of the questions having kappa values of 0.8 or higher, and the average kappa value for each of the eight domains ranging from 0.76 to 0.95. The 54 men and 95 women had a mean age of 79 years. Thirty-four percent of individuals suffered pain daily. Eighty percent tired easily; 52 percent were breathless on exertion; and 19 to 53 percent had one or more other symptoms, including change in sleep pattern, dry mouth, nausea and vomiting, anorexia, breathlessness at rest, constipation, and diarrhea. The number of symptoms an individual reported increased as the estimated time until death declined. The "clinician friendly" RAI-PC can be used in multiple sites of care to facilitate both care planning and case mix and outcomes research.

Adult↗

PubMedDate not supplied

Humerus shaft fractures in young children: accident or abuse?

We performed a retrospective review of 34 humerus shaft fractures (HSFs) in children younger than 3 years to determine the frequency of child abuse in young children with this injury. Data were obtained from hospital records (including previous and subsequent emergency, clinic, and inpatient notes), radiographs, and county childprotective services. Cases were reviewed independently by four physicians and were classified as probable abuse, probable not abuse, and indeterminate. Only 18% were classified as probable abuse. The history and findings other than the fracture itself were critical in establishing cause. Neither age nor fracture pattern is pathognomonic of abuse, but suspicion should remain high. A detailed history, complete physical examination, and appropriate radiographic investigation are required in every case either to make the diagnosis of abuse or to avoid the trauma of a false accusation.

Accidents↗