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Biomedical subjects

L Dick

Publications and source records attributed to L Dick.

8 recordsLinked to original sources
PubMed1992

Agraphia in dementia of the Alzheimer type.

This study describes graphic errors made in writing a simple sentence in 368 healthy older adults and individuals in different stages of dementia of the Alzheimer type. Errors of agraphia were present in both healthy and demented people and, in general, increased with the severity of dementia. The errors of agraphia were not correlated with measures of aphasia or psychometric measures of language and motor performance. Writing skill may represent procedural memory, and agraphia errors indicate alterations in long-term memory in dementia of the Alzheimer type.

Aged↗
PubMed1992

Nociceptive considerations in treating with counterstrain.

The proprioceptive mechanistic model of somatic dysfunction proposed by Korr is accepted as the neurophysiologic basis of counterstrain by the developer of that manipulative technique. We suggest that the physician should also take into account the physical damage, if any, that the original trauma produced. We propose that with tissue injury, nociceptive reflexes could produce patterns of motion restriction opposite that predicted by a solely proprioceptive model. A nociceptive component is suggested as an explanation for the origin and maintenance of somatic dysfunction and its response to the counterstrain technique. In actuality, both proprioceptive and nociceptive responses may occur in dysfunctional states. Other physiologic responses also may be involved. These views are consistent with clinical experience.

Humans↗
PubMed1991

Radiologic insertion of Hickman catheters in HIV-positive patients: infectious complications.

Ninety-six patients undergoing radiologically guided placement of 104 Hickman catheters were grouped according to their human immunodeficiency virus (HIV) serologic status. Infectious complications were categorized according to their severity (local or systemic) and time of occurrence (periprocedural or late). The number of infectious complications per 100 indwelling catheter days was calculated. Among the 14 catheter placements in 13 HIV-positive patients, two systemic infections occurred, resulting in a 14% overall infection rate and 0.18 infectious complications per 100 indwelling catheter days. The remaining 83 HIV-negative patients underwent 90 Hickman catheter placements. Nine infectious complications (10%) were noted in the 90 catheters, translating into 0.19 infectious complications per 100 indwelling catheters days. These results suggest no significant (relative risk [RR] of 1.4 and .95) difference in infectious complication rates encountered in HIV-positive patients compared with the general population. This supports the clinical usefulness of Hickman catheter placement in HIV-positive patients, although many additional HIV-positive patients must be evaluated to achieve an acceptable level of statistical confidence.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Metabolism of vasoactive peptides by plasma and purified renal aminopeptidase M.

Aminopeptidase M (AmM; EC 3.4.11.2) is a membrane-bound peptidase present on renal brush border and vascular plasma membrane. In the present study, AmM, purified from rabbit kidney cortex, produced a single immunoprecipitin line against AmM antisera, hydrolyzed alanyl-, leucyl- and arginyl-beta-naphthylamides at rates of 5.1 +/- 0.5, 3.9 +/- 0.5 and 2.6 +/- 0.3 mumol/min/mg, respectively, exhibited little or no alpha-glutamyl-, aspartyl- or glycyl-prolyl-naphthylamidase activities (less than or equal to 0.14 mumol/min/mg), and was inhibited by o-phenanthroline, amastatin (IC50 = 400 nM) and bestatin (IC50 = 6 microM). The alanyl-naphthylamidase activity of unfractionated rabbit plasma was found to be identical to purified AmM regarding relative rates of hydrolysis of alanyl-, leucyl- and arginyl-naphthylamides (100:79:42), pH optimum, and inhibition profile. In comparative studies with the purified enzyme, immunoreactive AmM accounted for essentially all of the alanyl-2-naphthylamidase activity of rabbit plasma. N-Terminal metabolism of (Met5)enkephalin by purified renal AmM was 3.92 +/- 0.69 mumol/min/mg, followed by somatostatin (1.25 mumol/min/mg), hepta(5-11)substance P (1.14 +/- 0.13 mumol/min/mg), (Asn1)angiotensin II (1.11 +/- 0.06 mumol/min/mg), angiotensin III (0.45 +/- 0.04 mumol/min/mg) and des(Asp1)-angiotensin I (0.36 +/- 0.04 mumol/min/mg). In contrast, substance P, bradykinin, (Sar1,Ala8)angiotensin II and neurokinin analogs containing modified N-termini (e.g. Ac-Arg) were resistant to hydrolysis by AmM. Peptide degradation was optimal at neutral pH and was inhibited by amastatin (IC50 = 200 nM) and bestatin (IC50 = 5 microM). Apparent Km values ranged from 15.7 +/- 0.4 microM for angiotensin III to 102 +/- 2 microM for (Met5)enkephalin. These data support a significant role for vascular and plasma AmM in the metabolism of circulating vasoactive peptides.

Amino Acid Sequence↗
PubMed1985

Vasopressin neuron survival in neonatal Brattleboro rats; critical factors in graft development and innervation of the host brain.

Previously it was found that grafts of supraoptic plus paraventricular areas from 19-day-old foetal normal rats survived in the third ventricle of the brain of 4- to 6-day-old, vasopressin-deficient Brattleboro pups, but could not alleviate their polyuria. In the present series, factors important in graft development were analysed. Again using day-19 fetuses as donors, anterohypothalamus grafts as well as grafts placed near a crushed median eminence survived relatively poorly, but showed the presence of vasopressin neurons immunocytochemically one month post-grafting. Homotopic grafting in the supraoptic nucleus, however, even failed to show surviving vasopressin neurons. Graft survival was improved by the use of donor tissue of fetuses younger than day 19. Parvocellular vasopressin cells were frequently seen, organized into clusters resembling the normal suprachiasmatic nucleus. However, magnocellular neurons, as normally seen in supraoptic and paraventricular nuclei, only survived grafting when taken between days 11 and 15 of fetal age. It was concluded that only immature vasopressin neurons survived grafting under the condition employed. Magnocellular neurons had a limited fiber outgrowth into the host brain and median eminence. Most large neurons only stained with non-specific neurophysin antiserum, not with specific vasopressin-associated neurophysin antiserum. Thin fibers of the parvocellular vasopressin neurons provided only occasional and sparse innervation of the host median eminence and lateral septum (one case), but several examples of massive fiber bundles running dorsally from graft into host brain were observed. These fibers terminated in the thalamic periventricular area, a nucleus that is normally innervated by the vasopressin neurons of the suprachiasmatic nucleus. The failure of the grafts to provide adequate vasopressinergic innervation of the host median eminence probably explains why none of the nearly 200 Brattleboro neonates operated upon showed any sign of relief of their diabetes insipidus. It suggests, however, that the present procedures might be useful in restoring central vasopressinergic functions in the developing Brattleboro rat.

Aging↗
PubMed1978

Perioperative suppression of the leukocyte migration inhibition assay in patients undergoing elective operations.

The effect of anesthesia and operation on immunity measured by leukocyte migration inhibition using streptokinase-streptodornase is reported in normal patients undergoing elective surgical procedures. Eight-five per cent of the patients exhibited postoperative immunosuppression, and this persisted for 60 days or longer in more than half of them. Despite this, no complication was encountered relating to wound healing or sepsis.

Adolescent↗
PubMed1976

Perspectives in malpractice.

Medical malpractice dates from Biblical days. And since then, much has been written on the subject. This article is a general overview of the historical, legal, and professional aspects of medical malpractice.

Legislation, Medical↗