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Biomedical subjects

S T Jackson

Publications and source records attributed to S T Jackson.

12 recordsLinked to original sources
PubMed1999

Late quaternary extinction of a tree species in eastern North America.

Widespread species- and genus-level extinctions of mammals in North America and Europe occurred during the last deglaciation [16,000-9,000 yr B.P. (by (14)C)], a period of rapid and often abrupt climatic and vegetational change. These extinctions are variously ascribed to environmental change and overkill by human hunters. By contrast, plant extinctions since the Middle Pleistocene are undocumented, suggesting that plant species have been able to respond to environmental changes of the past several glacial/interglacial cycles by migration. We provide evidence from morphological studies of fossil cones and anatomical studies of fossil needles that a now-extinct species of spruce (Picea critchfieldii sp. nov.) was widespread in eastern North America during the Last Glacial Maximum. P. critchfieldii was dominant in vegetation of the Lower Mississippi Valley, and extended at least as far east as western Georgia. P. critchfieldii disappeared during the last deglaciation, and its extinction is not directly attributable to human activities. Similarly widespread plant species may be at risk of extinction in the face of future climate change.

Biological Evolution↗
PubMed1995

Transparency of one-handed Amer-Ind hand signals to nonfamiliar viewers.

Thirty non-brain-damaged adults viewed 104 videotaped Amer-Ind hand signals. The majority of these hand signals were produced with one hand; 60 originally one-handed gestures and 31 left-hand adaptations of two-handed gestures were included in the data analyses. Nineteen subjects were between the ages of 20 and 30 years (younger group), and 11 subjects were between the ages of 50 and 69 years (older group). After viewing each hand signal twice in succession, the subjects wrote at least one word for that signal's meaning. The mean percentage of one-handed signals correctly identified was 48.2%; these signals varied widely in transparency (0% to 100%). The left-hand adaptations were significantly lower in transparency than the originally one-handed signals. The younger and older subjects did not differ in the mean percentage of one-handed signals they identified correctly (49.0% and 46.4%, respectively). However, some individual hand signals were easier for the younger subjects to identify; the opposite was also true.

Adult↗
PubMed1990

On prognostic research in adult neurologic disorders.

This note suggests some changes in variable selection and operationalization for research on prognosis in adult neurologic communicative disorders. The issues raised are relevant to both broad prognostic questions concerning extent of recovery, and focused questions regarding candidacy and treatment efficacy.

Adult↗
PubMed1989

The effect of semantic and syntactic structure on verbal memory in Alzheimer's disease.

This study examined the ability of 17 patients with Alzheimer's disease and 17 normal-old subjects to recall short sentences that were normal, or had a disruption in either their semantic structure, their syntactic structure, or both their semantic and syntactic structure. Results showed that sentence recall performance was affected similarly in the demented and normal-old subjects by both the syntactic and semantic structure of the sentences. The presence of either type of language structure appeared to allow both normal and demented subjects to organize strings of words into multiword chunks for more efficient memory encoding.

Aged↗
PubMed1988

Brachial-plexus palsy in the newborn.

Twenty-one patients who had twenty-three brachial-plexus palsies resulting from trauma at birth were studied over a three and one-half year period, between July 1983 and December 1986. The incidence of this group of injuries was 2.5 per 1,000 live births. There were fourteen palsies of the fifth and sixth cervical nerves; eight of the fifth, sixth, and seventh cervical nerves; and one of the entire brachial plexus. Two patients were lost to follow-up shortly after birth. Of the remaining nineteen patients (twenty-one palsies), fifteen (seventeen palsies) had full recovery at an average of three months (range, two weeks to twelve months), and four (four palsies) had residual paralysis of the upper extremity at more than twenty-six months. We concluded that the newborn who has a brachial-plexus palsy has a favorable prognosis for complete recovery.

Apgar Score↗
PubMed1987

Fractures of the distal part of the fibula with associated disruption of the deltoid ligament. Treatment without repair of the deltoid ligament.

The results in twenty-four patients who were treated for a distal fibular fracture and disruption of the deltoid ligament were studied, using subjective, objective, and radiographic criteria, over a period of at least two years. Nineteen (90 per cent) of the twenty-one patients who were treated without repair of the deltoid ligament had a good or excellent result. All but two of these patients were unrestricted in the ability to walk and run and had no pain during the activities of daily living. No patient had instability of the ankle. At follow-up, the range of motion of the ankle was within 15 degrees of that of the uninjured ankle in 90 per cent of the patients. Only one ankle had radiographic evidence of narrowing of the joint space. The three patients in whom the deltoid ligament was repaired did not have as good a result as the twenty-one patients in whom it was not, but this group was too small to permit valid comparisons. We concluded that exploration of the medial side of the ankle and repair of the deltoid ligament are not necessary unless reduction of the lateral malleolus fails to reduce the talus within the ankle mortise.

Activities of Daily Living↗
PubMed1983

Surgery for involutional entropion.

Surgery for involutional entropion must correct horizontal eyelid laxity, vertical laxity, and overriding of the tarsus by the infra-tarsal tissues. The surgery should give lasting functional and pleasing cosmetic results. These goals are achieved with: 1) a blepharoplasty incision and reflection of a skin-muscle flap; 2) excision of a wedge of eyelid tissue at the lateral canthus; 3) barrier sutures or tuck of the retractors; 4) reattachment of the lid to the lateral orbital rim; and 5) excision of excess skin.

Aged↗
PubMed1980

A new probe for silicone intubation of the lacrimal drainage system.

A new probe is described for silicone intubation of the lacrimal drainage system. The probe is a 1-mm hollow, malleable stainless steel tube. The leading end is rounded and smooth. Silicone tubing is fitted inside the trailing end of the probe, which is swaged over the tubing. The complete instrument consists of two such probes attached to each end of a 30-cm length of silicone tubing. Because the silicone is swaged onto the probe, the possibility of slippage of the tubing from the probe is eliminated.

Humans↗
PubMedDate not supplied

Test-retest reliability of three aphasia tests: performance of non-brain-damaged older adults.

This study was designed to assess the test-retest reliability of three aphasia tests. The Auditory Comprehension Test for Sentences (ACTS), the Boston Naming Test (BNT), and the Reading Comprehension Battery for Aphasia (RCBA) were administered on two separate occasions to 31 non-brain-damaged adults aged 50 to 76 years. The results showed acceptable score stability for all three aphasia tests. Sixty-eight percent of the time, older non-brain-damaged adults would be expected to score within 4.0% or less of the total number of test items on repeated testing.

Aged↗
PubMedDate not supplied

The validity of reading comprehension therapy materials.

This study examines the degree to which reading comprehension therapy materials measure reading comprehension. Thirty-six non-brain-damaged adults (18 females, 18 males) ranging in age from 55 to 75 years participated. They answered written multiple-choice questions from aphasia therapy workbooks before and after reading the paragraphs (n = 40) to which the questions related. Results showed that for each of four sets of workbook materials, subjects answered an average of 24% to 49% more of the questions after reading the paragraphs relative to the number they answered before reading the paragraphs. For questions that could not be answered using one's prior knowledge, subjects were more dependent on having to read the paragraph in order to answer the questions correctly. Based on binomial probabilities, at least half of the questions from 32/40 paragraphs were answered correctly at greater than chance levels without reading the related paragraph.

Aged↗