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Biomedical subjects

A T Johnson

Publications and source records attributed to A T Johnson.

At least 73 records · Page 4Linked to original sources
PubMed1985

Development of the subretinal space in the preterm human eye: ultrastructural and immunocytochemical studies.

To investigate the development of the subretinal space in the human infant, eyes were obtained from 12 live-born, anomaly-free, preterm infants from 20 to 32 weeks gestation and from one 3-month postterm infant. The retinas were studied by light microscopy, electron microscopy, and immunocytochemistry. The immunocytochemical studies utilized rabbit antiserum against purified bovine interstitial retinol binding protein (IRBP). A subretinal space containing IRBP was present in the central retina at 20 weeks and extended further into the periphery (expressed as a percentage of the distance from the optic disc to the ora serrata in the temporal hemisphere) as the retina developed. At 28 weeks, IRBP was absent only from the most peripheral 25% of the retina and reached the temporal ora serrata at 32 weeks. At 3 months postterm, IRBP immunofluorescence outlined fully developed photoreceptors, which were present from the optic disc to the ora serrata. The appearance of IRBP in the subretinal space correlated with the development of the first photoreceptor outer segment discs.

Fluorescent Antibody Technique↗
PubMed1985

Microcomputer program for the design of digital filters.

The program presented here is intended to be a design device and learning tool for digital filters. Digital filters designed with the program can be implemented by incorporation within the data analysis programs of the user. The program is written in BASIC for use with the IBM-PC, is intended to be user-friendly, and includes a great deal of filter assistance not found in other programs. An example of program use shows how one filter can be used to remove noise from respiratory waveform data.

Analog-Digital Conversion↗
PubMed1984

Multidimensional curve fitting program for biological data.

A program written for use with the IBM-PC can be used to find least squares solutions to linearized multidimensional equations. The program is 'user-friendly' by requiring little from the user except to make decisions; most responses can be entered by a single keystroke. Once data are entered by the user, they can be repeatedly manipulated, graphed, and correlated. Many models relating data variables can be tried relatively easily, and best fit results found. Examples using respiratory mechanical data illustrate the ease of model comparisons.

Biometry↗
PubMed1982

Extra-cranial tumours of the infratemporal fossa.

We have reviewed the world literature on infra-temporal fossa tumours and have presented a further 12 cases diagnosed by ourselves. The similarity in incidence of the 3 types of tumor (1) primary, (ii) contiguous and (iii) metastatic between our series and world experience has been observed. The anatomy of the intra-temporal fossa has been described in detail and the connection between the infra-temporal fossa and the parapharyngeal space is clarified. We also have emphasised the relationship between the deep lobe of the parotid gland and the infra-temporal fossa, and the improbability of deep lobe tumours spreading to the infra-temporal fossa, although superficial lobe tumours may do so by invasion through the mandibular notch. Attention has been direct to the frequent presentation of these tumours in the superior gingivo-buccal sulcus. Since facial pain is frequently a presenting symptom of these tumours many months before diagnosis, emphasis has been laid on the desirability of CAT scanning forming an integral part of the investigation, especially in patients complaining of undiagnosed facial pain.

Adolescent↗
PubMed1980

Correlation of WBGT and botsball sensors.

The standard method for measuring human environmental heat stress is the WBGT. The WBGT apparatus is cumbersome and difficult to relate to standard psychrometric parameters or to other environmental measures such as the Botsball. The work presented in this paper was derived from thermodynamic and heat transfer considerations with corrections applied to be consistent with published experimental results.

Air↗
PubMed1976

The energetics of mask wear.

Experimental data further defining the region of predominant respiratory stress is presented. Within this region, energy requirements of respiration increase disproportionately to the overall energy expenditure of the body as excercise intensity increases. Addition of a mask accentuates this tendency, especially since no physiological compensation is possible in mask parameters. Mask technology has improved masks to the point where they no longer dominate the man-mask system, but instead contribute resistances and dead volumes approximately equal to those naturally occurring in man. Modeling base on minimization of respiratory energy rate of expenditure in the human is applied to this man-mask system and predictions are made which to this point have been nearly impossible to obtain from experimental data.

Body Temperature↗
PubMed1975

Mask design considerations.

Mask design should be based more strongly on physiological data obtained from working individuals. This paper is a compendium of pertinent information as well as a guide to better design. An indication of the trends of current research is also given.

Adaptation, Physiological↗