M protein gene type distribution among group A streptococcal clinical isolates recovered in Mexico City,Mexico, from 1991 to 2000, and Durango,Mexico, from 1998 to 1999: overlap with type distribution within the United States

To examine the type distribution of pathogenic group A streptococcal (GAS) strains in Mexico, we determined the emm types of 423 GAS isolates collected from ill patients residing in Mexico (Durango or Mexico City). These included 282 throat isolates and 107 isolates from normally sterile sites. Of the other isolates, 38 were recovered from other miscellaneous infections. A total of 31 different emm types were found, revealing a broad overlap between commonly occurring emm types in Mexico and the United States. The information obtained in this study is consistent with the possibility that multivalent, M type-specific vaccines prepared for GAS strain distribution within the United States could theoretically protect against the majority of GAS strains causing disease in the two cities surveyed in Mexico.     

Plasma skimming efficiency of human blood in the spiral groove bearing of a centrifugal blood pump

Journal of Artificial Organs - This work investigates the plasma skimming effect in a spiral groove bearing within a hydrodynamically levitated centrifugal blood pump when working with human blood...     

Real‐Time Observation of Thrombus Growth Process in an Impeller of a Hydrodynamically Levitated Centrifugal Blood Pump by Near‐Infrared Hyperspectral Imaging

Understanding the thrombus formation in cardiovascular devices such as rotary blood pumps is the most important issue in developing more hemocompatible devices. The objective of this study was to develop a hyperspectral imaging (HSI) method to visualize the thrombus growth process within a rotary blood pump and investigate the optical properties of the thrombus. An in vitro thrombogenic test was conducted using fresh porcine blood and a specially designed hydrodynamically levitated centrifugal blood pump with a transparent bottom. The pump rotating at 3000 rpm circulated the blood at 1.0 L/min. The bottom surface of the pump was illuminated with white light pulsed at the same frequency as the pump rotation, and the backward‐scattered light was imaged using the HSI system. Using stroboscopic HSI and an image construction algorithm, dynamic spectral imaging at wavelengths ranging from 608 to 752 nm within the rotating pump was achieved. After completing the experiment, we collected the red thrombus formed in the pump impeller and quantified the thrombus hemoglobin concentration (Hb_thrombus). The spectrum changed around the center of the impeller, and the area of change expanded toward the impeller flow path. The shape corresponded approximately to the shape of the thrombus. The spectrum change indicated that the light scattering derived from red blood cells decreased. The Hb_thrombus was 4.7 ± 1.3 g/dL versus a total hemoglobin of 13 ± 0.87 g/dL. The study revealed that Hb_thrombus was reduced by the surrounding blood flow.     

New Generation Extracorporeal Membrane Oxygenation With MedTech Mag‐Lev,a Single‐Use,Magnetically Levitated,Centrifugal Blood Pump: Preclinical Evaluation in Calves

We have evaluated the feasibility of a newly developed single‐use, magnetically levitated centrifugal blood pump, MedTech Mag‐Lev, in a 3‐week extracorporeal membrane oxygenation (ECMO) study in calves against a Medtronic Bio‐Pump BPX‐80. A heparin‐ and silicone‐coated polypropylene membrane oxygenator MERA NHP Excelung NSH‐R was employed as an oxygenator. Six healthy male Holstein calves with body weights of about 100 kg were divided into two groups, four in the MedTech group and two in the Bio‐Pump group. Under general anesthesia, the blood pump and oxygenator were inserted extracorporeally between the main pulmonary artery and the descending aorta via a fifth left thoracotomy. Postoperatively, both the pump and oxygen flow rates were controlled at 3 L/min. Heparin was continuously infused to maintain the activated clotting time at 200–240 s. All the MedTech ECMO calves completed the study duration. However, the Bio‐Pump ECMO calves were terminated on postoperative days 7 and 10 because of severe hemolysis and thrombus formation. At the start of the MedTech ECMO, the pressure drop across the oxygenator was about 25 mm Hg with the pump operated at 2800 rpm and delivering 3 L/min flow. The PO₂ of the oxygenator outlet was higher than 400 mm Hg with the PCO₂ below 45 mm Hg. Hemolysis and thrombus were not seen in the MedTech ECMO circuits (plasma‐free hemoglobin [PFH] < 5 mg/dL), while severe hemolysis (PFH > 20 mg/dL) and large thrombus were observed in the Bio‐Pump ECMO circuits. Plasma leakage from the oxygenator did not occur in any ECMO circuits. Three‐week cardiopulmonary support was performed successfully with the MedTech ECMO without circuit exchanges. The MedTech Mag‐Lev could help extend the durability of ECMO circuits by the improved biocompatible performances.     

Detection of thrombosis in a magnetically levitated blood pump by vibrational excitation of the impeller

The use of contactless support technology for the impeller has led to an increase in the durability of ventricular assist devices (VADs), and these have been in clinical use worldwide. However, pump thrombosis and stroke are still issues to be solved. We have developed a method for detecting the thrombosis in a magnetically levitated blood pump without the need for additional sensors or other equipment. In the proposed method, a sinusoidal current is applied to the electromagnets used for the magnetic bearing, resulting in vibration of the impeller. The phase difference between the current and displacement of the impeller increases with pump thrombosis. First, we describe the principle by which the pump thrombosis is detected. Pump thrombosis reduces the narrowest fluid gap in the pump and this gives rise to a change in the phase difference. Second, we report on experiments in which we changed the narrowest fluid gap using oriented polypropylene tape and showed that decreasing the narrowest fluid gap resulted in an increase in phase difference. For these experiments, the measurements were repeated three times for each condition. Third, we examine the relationship between the pump thrombosis and the phase difference evaluated by observations of the underside of the impeller when operating the pump with porcine blood. Since light was unable to penetrate the blood layer, the erythrocytes were removed for this observation. Only one observation was made. The results showed the phase difference rapidly increased at the same moment when the pump thrombosis was observed. This implies the proposed method has the potential to detect the early stages of pump thrombosis. Finally, in vitro experiments to detect thrombosis when using whole porcine blood in the pump were conducted. The experiment was carried out five times. To intentionally form a thrombus inside the pump, the activated clotting time was controlled to be less than 200 s. In every case, the phase difference increased by more than one degree after tens of minutes. Then, the pump was disassembled and a small amount of pump thrombosis was observed. We conclude that real-time diagnosis of pump thrombosis may be realized by measuring the phase difference without the need for additional sensors.     

Feasibility of the Optical Imaging of Thrombus Formation in a Rotary Blood Pump by Near‐Infrared Light

Blood coagulation is one of the primary concerns when using mechanical circulatory support devices such as blood pumps. Noninvasive detection and imaging of thrombus formation is useful not only for the development of more hemocompatible devices but also for the management of blood coagulation to avoid risk of infarction. The objective of this study is to investigate the use of near‐infrared light for imaging of thrombus formation in a rotary blood pump. The optical properties of a thrombus at wavelengths ranging from 600 to 750 nm were analyzed using a hyperspectral imaging (HSI) system. A specially designed hydrodynamically levitated centrifugal blood pump with a visible bottom area was used. In vitro antithrombogenic testing was conducted five times with the pump using bovine whole blood in which the activated blood clotting time was adjusted to 200 s prior to the experiment. Two halogen lights were used for the light sources. The forward scattering through the pump and backward scattering on the pump bottom area were imaged using the HSI system. HSI showed an increase in forward scattering at wavelengths ranging from 670 to 750 nm in the location of thrombus formation. The time at which the thrombus began to form in the impeller rotating at 2780 rpm could be detected. The spectral difference between the whole blood and the thrombus was utilized to image thrombus formation. The results indicate the feasibility of dynamically detecting and imaging thrombus formation in a rotary blood pump.     

Epidemic study of pet allergy in Wakayama Prefecture

In Japan, the number of households who have pets has gradually increased, together with the number of people who have pet allergies. Many reports exist on pollen and mite allergy, but few on pet allergy. We conducted an epidemic study in 531 first-year junior high school students in Wakayama prefecture in 1999. Questionnaires covered allergy and measurement of total IgE antibody using CAP system (Pharmacia Co. Ltd.) and specific IgE antibody using MAST26 system (Hitachi chemical Co. Ltd.). Of 306 students having pets, 11 were allergic to dogs, 11 to cats, 8 to both, and 1 to rabbits. Clinical symptoms were various. No differences in symptoms were observed among allergens. Serum total IgE tended to increase in students who suffered from pet allergies. Positive rates of specific IgE antibodies were high in mites and Japanese cedar pollen (36.7% for mites and 37.0% for Japanese cedar pollen), and also in dogs and cats (15.4% for dogs and 18.2% for cats). Specific dog and cat IgE antibodies increased significantly (p = 0.033 for dog and for p < 0.0001 cat), but no significant correlation was found between the positive specific IgE antibody and history of pet keeping.     

A case with diffuse vasospasm after perimesencephalic nonaneurysmal subarachnoid hemorrhage]

Perimesencephalic nonaneurysmal subarachnoid hemorrhage(PNSH), defined as bleeding in the cisterns around the midbrain with a negative four-vessel angiographic study, is uniformly associated with an excellent outcome without associated rebleeding or symptomatic vasospasm. Angiographic vasospasm is uncommon in patients with this disease, and if vasospasm is present, severe and diffuse angiographical vasospasm is rare. We report a case with PNSH who developed severe and diffuse angiographic vasospasm. The patient was a 52-year-old woman who suffered an acute severe headache. We diagnosed PNSH from CT and angiographical findings, and treated her conservatively. Serial angiography, that was performed on the fourteenth day after hemorrhage, showed diffuse and severe angiographic vasospasm affecting both the anterior and the posterior circulation. She was treated with normovolemia, and remained no neurological symptom. Follow-up MR angiography showed improvement of the angiographic vasospasm. When the presence of diffuse and severe vasospasm is detected, a diagnosis of PNSH should not be excluded.     

Oral manifestations of acute promyelocytic leukemia.

A study was conducted of 16 patients with acute promyelocytic leukemia. The most common oral manifestations were hemorrhagic diathesis and leukemic involvement. There was gingival bleeding, petechiae, and ecchymosis of the oral mucosa, massive infiltration-induced gingival swelling, ulcerative glossitis, swelling of the tonsils, and facial palsy. Inflammatory stomatitis also occurred. Patients with acute promyelocytic leukemia had a higher incidence and severity of oral bleeding than those with other types of acute leukemia. However, the oral findings in our series were not necessarily specific for acute promyelocytic leukemia because the same oral symptoms occur in other forms of acute leukemia.