Alzheimer's Disease: A Decreased Cerebral Blood Flow to Critical Intraneuronal Elements Is the Cause.

Normally, an adequate cerebral blood flow arrives at individual cerebral neurons in which the blood flow augments activity of intraneuronal mitochondria, which is the source of intraneuronal ATP, the energy source of cerebral neurons. With a decrease in cerebral blood flow that can occur as a function of normal aging phenomena, less blood results in decreased mitochondria, decreased ATP, and a decrease in neuronal activity, which can eventually lead to Alzheimer's disease. It has been found that placement of the omentum directly on an Alzheimer's disease brain can lead to improved cognitive function.

Potential improvement of survival statistics for glioblastoma multiforme (WHO IV).

The present-day treatment of a glioblastoma multiforme IV (glioblast) is by surgery, radiation, and chemotherapy. Unfortunately, the current treatment has not significantly improved the survival statistics of this tumor. There are now two relatively new surgical procedures that may improve the survival statistics of this malignancy. One of these procedures is the intraoperative use of the drug 5-aminovolumic acid (ALA), which fluoresces a red color in malignant brain tissue that is not observed in normal brain tissue. This allows a neurosurgeon to distinguish brain tissue infiltrated by malignant cells, thus allowing a more complete resection of the tumor. Another procedure that has the potential to improve the survival statistics of glioblasts is the use of the omentum. Direct placement of the omentum on a brain infiltrated by malignant cells would allow omental blood vessels, known to be completely clear of endothelial cells, to penetrate directly into the underlying brain. The blood flow through omental blood vessels could be expected to carry chemotherapeutic agents throughout the involved brain, thereby totally bypassing the blood-brain barrier. Combining a tumor resection using 5-ALA and placing the omentum on the brain may prove instrumental in improving the survival statistics of patients suffering from a glioblast.

Improving the extinction bandwidth of MMI chalcogenide photonic chip based MIR nulling interferometers.

Research into planets beyond our own star system has until recently relied on indirect imaging methods. Direct imaging methods are now establishing a foothold in the hunt for alien planets and habitable worlds. Nulling interferometry is a promising approach for suppressing the host star brightness and resolving surrounding planets. A key requirement in this method is the interference of light from multiple telescopes/baselines and free space optical devices have already rendered images of other worlds. Photonic chip based systems are also becoming accepted as means of accomplishing this but require, in particular, wide bandwidth, high precision on chip beam splitters. In this paper a design improvement is outlined to one of the most fabrication tolerant integrated beam splitter components that significantly increases its coupling bandwidth and therefore its bandwidth at high extinction. Preliminary experimental results from a fabricated device are also shown. The predicted bandwidth spans 3.8 - 4.1 µm at an extinction of ∼50 dB but at the expense of increasing the loss to 0.6 dB in transmission.

Fabrication tolerant chalcogenide mid-infrared multimode interference coupler design with applications for Bracewell nulling interferometry.

Understanding exoplanet formation and finding potentially habitable exoplanets is vital to an enhanced understanding of the universe. The use of nulling interferometry to strongly attenuate the central star's light provides the opportunity to see objects closer to the star than ever before. Given that exoplanets are usually warm, the 4 µm Mid-Infrared region is advantageous for such observations. The key performance parameters for a nulling interferometer are the extinction ratio it can attain and how well that is maintained across the operational bandwidth. Both parameters depend on the design and fabrication accuracy of the subcomponents and their wavelength dependence. Via detailed simulation it is shown in this paper that a planar chalcogenide photonic chip, consisting of three highly fabrication tolerant multimode interference couplers, can exceed an extinction ratio of 60 dB in double nulling operation and up to 40 dB for a single nulling operation across a wavelength window of 3.9 to 4.2 µm. This provides a beam combiner with sufficient performance, in theory, to image exoplanets.

Flow patterns and preferred sites of atherosclerotic lesions in the human aorta - I. Aortic arch.

OBJECTIVES: To elucidate the role of fluid mechanical factors in the localized genesis and development of atherosclerotic lesions in man. METHODS: Flow patterns and preferred sites of atherosclerotic lesions in the human aortic arch were studied in detail using isolated transparent aortic trees prepared from humans postmortem and by means of flow visualization of tracer polystyrene microspheres, using cinemicrographic techniques. RESULTS: Under the condition of steady flow that simulated mid-systole, the flow in the aortic arch consisted of three major components; (i) a straight flow to the brachio-cephalic artery located close to the right dorsal wall of the ascending aorta; (ii) a quasi-parallel undisturbed flow located close to the common median plane of the aortic arch and its side branches, and (iii) a clockwise slow, spiral secondary flow located dominantly near the left ventral wall of the aortic arch. Thus, looking down the aorta from its origin, the flow in the aortic arch appeared as a single helical flow revolving in a clockwise direction. CONCLUSIONS: Atherosclerotic lesions were found mainly in regions of low wall shear stress such as the proximal lip of the orifice of each side branch where a slow recirculation flow formed, and the left ventral wall of the aortic arch where a slow spiral secondary flow formed.

Flow patterns and preferred sites of atherosclerotic lesions in the human aorta - II. Abdominal aorta.

OBJECTIVE: As in Part I, to elucidate the role of fluid mechanical factors in the localized genesis and development of atherosclerotic lesions in man, here in the abdominal aorta. METHODS: Flow patterns and preferred sites of atherosclerotic lesions in the aorta were studied in detail using the same isolated transparent aortic trees prepared from humans postmortem and the flow visualization and cinemicrographic techniques as in Part I. RESULTS: Under steady flow simulating mid-systole, the flow was found to be disturbed at the aorto-celiac and aorto-superior mesenteric artery junctions by the formation of complex secondary and adverse flows along the lateral and posterior walls of the abdominal aorta. More complex secondary and adverse flows formed at the branching sites of the left and right renal arteries. Furthermore, considerable interactions occurred between the secondary and adverse flows formed at the branching sites of the above four arteries, resulting in the formation of a large and long recirculation zone along the lateral and posterior walls of the abdominal aorta corresponding to these branches. The velocity profile was almost flattened throughout the entire length of the descending aorta. CONCLUSIONS: Atherosclerotic lesions were found mainly at the posterior and lateral walls of the abdominal aorta where slow adverse and recirculation flows formed and where wall shear stress was low.

Benefit of omental blood flow in Alzheimer's disease: effect on deteriorating neurons.

It has been commonly believed that a decrease in cerebral blood flow (CBF), which routinely occurs in Alzheimer's disease (AD), results from the death of critical intracerebral neurons that no longer require the maintenance of an adequate blood supply. This belief is presently being challenged by the idea that it is not neuronal death that causes a decrease in CBF, but actually a decrease in the CBF which leads to the death of neurons seen in AD. In association with dead neurons located within the AD brain are varying numbers of deteriorating neurons. Increasing the CBF to still viable but deteriorating neurons in AD is believed to delay and even improve the clinical manifestations of AD. This increase in CBF has proven effective in treating a group of patients with AD. The increase in CBF was accomplished surgically by placing an intact pedicled omentum directly on the AD brain. While surgery is not a long-term answer in the treatment of AD, the surgical procedure should be evaluated by a carefully controlled study while awaiting the future development of a pharmaceutical method to control the disease.

Pyloric valve transposition as substitute for a colostomy in humans: a preliminary report.

BACKGROUND: The purpose of this article was to show that a transposed pyloric valve (PV) can be mobilized to the perianal region and can function as a replacement for an excised rectal sphincter. Surgical research on animals has shown that a vascularized PV can be taken out of gastroduodenal continuity, transposed to the pelvic region with maintenance of fecal control when positioned in the anal area. METHODS: The surgical procedure has recently proved successful in humans in which the distal end of the left colon was anastomosed to the proximal end of the transposed PV with the distal end of the PV sutured to the skin in the perianal area as the replacement for an excised rectal sphincter. Fecal control was established after the operation. RESULTS: The PV healed in an anal position in humans with no apparent anatomic or physiological reasons to suggest that the operation might not be successful in the future as a substitute for a surgically excised or a severely damaged rectal sphincter. CONCLUSIONS: A vascularized PV supplied by the gastroepiploic artery within an omental pedicle can serve as a replacement for an excised rectal sphincter, thus eliminating the need for a permanent colostomy.

A new approach to the treatment of Alzheimer's disease: the need for a controlled study.

It has been widely believed that decreased cerebral blood flow (CBF), known to occur in Alzheimer's disease (AD), is the result of neuronal degeneration that causes a decrease in the need for adequate CBF. There is new interest in the idea, however, that it is not neuronal degeneration that leads to decreased CBF to critical neurons, but it is the decrease in CBF which is the cause of the neuronal deterioration seen in AD patients. In order to increase CBF to the AD brain, an operation called omental transposition has been developed in which an intact elongated omental pedicle, when placed directly on the brain, provides additional CBF and other biological nutrients to the brain. It is understandable that AD patients are awaiting a method to control their disease, but this may take years to become available. Placing the omentum on the AD brain has demonstrated increased CBF which may be the reason that several studies have shown that omental transposition to the brain can improve the cognitive ability of AD patients who have undergone the operation. What is needed is a prospective controlled study that could scientifically establish the benefit of the procedure.

Treatment of communicating hydrocephalus by a lumbo-omental shunt: case report.

Based on preliminary experiences from the early 1970s, a patient with chronic and severe communicating hydrocephalus has been successfully treated with transposition of an omental pedicle to the lumbar subarachnoidal space. This patient, who suffered from congenital toxoplasmosis, at the age of 29 years had undergone no fewer than 82 shunt revisions. In the 5-year follow-up after treatment, she has had no further surgery or other treatment. She is in excellent condition and has demonstrated definite signs of improved CSF circulation. This case report confirms that a pedicle of the omentum may serve as an effective CSF absorber in patients presenting with persistent failures with conventional treatments of communicating hydrocephalus, avoiding the use of any implanted foreign material.