High-density data acquisition system and signal preprocessor for interfacing with microelectromechanical system-based biosensor arrays.

Microelectromechanical system (MEMS) development has become an active area for research in over the last decade. This area has advanced rapidly in recent years due to the potential ability of MEMS devices to perform complex functions in a smaller area. There is also the prospect to develop devices that can (1) be easily manufactured, (2) offer low power consumption, and (3) reduce waste. Especially in the BioMEMS area these advantages are important in terms of applied devices for biosensing, clinical diagnostics, physiological sensing, flow cytometry, and other lab-on-a-chip applications. However, one major obstacle that has been overlooked is the interface of these microdevices with the macroworld. This is critical to enable applications and development of the technology, as currently testing and analysis of data from these devices is mostly limited to generic microprobe stations. New advancements in BioMEMS have to occur in concert with the development of data acquisition systems and signal preprocessors to fully appreciate and test these developing technologies. In this work, we present the development of a cost effective, high throughput data acquisition system (Bio-HD DAQ) and a signal preprocessor for a MEMS-based cell electrophysiology lab-on-a-Chip (CEL-C) device. The signal preprocessor consists of a printed circuit board mounted with the CEL-C device and a 64-channel filter/amplifier circuit array. The data acquisition system includes a high-density crosspoint switching matrix that connects the signal preprocessor to a 16-channel, 18 bit, and 625 kSs DAQ card. Multimodule custom software designed on LABVIEW 7.0 is used to control the DAQ system. While this version of the Bio-HD DAQ system and accompanying software are designed keeping in view the specific requirements of the CEL-C device, it is highly adaptable and, with minor modifications, can become a generic data acquisition system for MEMS development, testing, and application.

Pneumocystis carinii. Taxonomy as viewed by electron microscopy.

Pneumocystis carinii is an opportunistic unicellular organism that can cause serious pulmonary infection in immunosuppressed patients. The taxonomy and classification of P. carinii has not yet been settled. The authors present transmission and scanning electron microscopic (TEM and SEM) observations of tissue from two patients with pulmonary Pneumocystis infections. The infectious organisms display marked variability in shape and size. They appear to divide by binary fission and lack motility organelles, Golgi apparatus, phagosomes, and lysosomes. The mitochondria and endoplasmic reticulum were poorly developed. The nucleus was rather ill defined, and there appeared to be asynchrony in the development of nuclear membranes and cytoplasm. The authors contend that there are firm ultrastructural evidences against the claim for a protozoan nature of Pneumocystis and in favor of its being a fungus, albeit of a primitive form, in which the mycelium is reduced to a unicellular state but the ability to sporulate is preserved.

Postsplenectomy pneumococcemia in adults.

We describe two adults with fulminant pneumococcemia and disseminated intravascular coagulation aftertraumatic splenectomy. One died in a few days, and the other survived with amputation of gangrenous toes and fingers. Although the relationship between the serious blood-borne bacterial infection with disseminated intravascular coagulation and lack of adequate splenic tissue has been well established, the mechanism is poorly understood and there are no specific therapeutic measures available. We review the literature in regard to the possible prophylactic measures and discuss the benefits of various measures.

Fine needle aspiration cytology of Tay-Sachs disease. A case report.

The fine needle aspiration cytology (FNAC) brain findings on a 6-year-old with Tay-Sachs disease are presented. These findings were compared with the FNAC findings on identical areas of a normal brain. Copious material was obtained from both cases. Marked loss of neurons, prominent gliosis, reactive microglia and scattered macrophages were hallmarks of Tay-Sachs disease. The findings were the same as those observed in the histopathology of Tay-Sachs disease. The normal brain, as expected, showed no such changes. It is concluded that FNAC has a great potential for diagnosis and follow-up of Tay-Sachs disease and other nonneoplastic neurologic diseases.

Correlation between Barr bodies and neutrophil drumsticks.

There is a marked difference between the frequencies of neutrophil nuclear drumsticks and mucosal cell Barr bodies in any given woman despite the fact that both represent an inactivated X chromosome. We present results of a prospective study carried out on 100 normal Saudi females to assess the statistical correlation between these two variables. We conclude that each is independent of the other. The lack of statistical correlation perhaps relates to maturational and nuclear configuration factors.