Variability of Hypericins and Hyperforin in Hypericum Species from the Sicilian Flora

Within Sicilian flora, the genus Hypericum (Guttiferae) includes 10 native species, the most popular of which is H. perforatum. Hypericum's most investigated active compounds belong to naphtodianthrones (hypericin, pseudohypericin) and phloroglucinols (hyperforin, adhyperforin), and the commercial value of the drug is graded according to its total hypericin content. Ethnobotanical sources attribute the therapeutic properties recognized for H. perforatum, also to other Hypericum species. However, their smaller distribution inside the territory suggests that an industrial use of such species, when collected from the wild, would result in an unacceptable depletion of their natural stands. This study investigated about the potential pharmacological properties of 48 accessions from six native species of Hypericum, including H. perforatum and five 'minor' species, also comparing, when possible, wild and cultivated sources. The variability in the content of active metabolites was remarkably high, and the differences within the species were often comparable to the differences among species. No difference was enlightened between wild and cultivated plants. A carefully planned cultivation of Hypericum seems the best option to achieve high and steady biomass yields, but there is a need for phytochemical studies, aimed to identify for multiplication the genotypes with the highest content of the active metabolites.

Phytochemical profiles, phototoxic and antioxidant properties of eleven Hypericum species - A comparative study

Hypericum is one out of the nine genera belonging to the botanical family Clusiaceae Lindl (syn. Hypericaceae Juss.; APG III, 2009). The genus contains 484 species spread worldwide, one of which, Hypericum perforatum, is largely used in folk medicine. The aim of this study was to evaluate the chemical composition, along with the antioxidant and phototoxic activity, of 11 Hypericum species grown in Sicily (H. perforatum L., H. aegypticum L., H. androsaemum L., H. calycinum L., H. hircinum L., H. hirsutum L., H. montanum L., H. patulum Thunb., H. perfoliatum L., H. pubescens Boiss., H. tetrapterum Fr.). Samples of flowering tops collected from these Hypericum species were extracted and analysed by high performance liquid chromatography with diode-array detection and mass spectrometry (HPLC-DAD-MS) to determine their content of main polyphenols, acylphloroglucinols, and naphthodianthrones. The extracts were also subjected to a photocytotoxic assay using murine fibroblast (NIH/3T3), and their antioxidant activity evaluated by means of Folin-Ciocalteau, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, and oxygen radical antioxidant capacity assays. Phytochemical analysis allowed us to identify and quantify 20 metabolites, each of them possessing a well-known biological activity. Furthermore, all examined species showed a good cytotoxic and antioxidant/radical scavenging activity. These results indicate that in addition to the well-known H. perforatum, at least other three species (H. tetrapterum, H. pubescens, and H. montanum) represent potential sources of biologically active compounds, and at least other two species (H. perfoliatum and H. tetrapterum), due to their phototoxicity are candidates for application in photodynamic therapy.

Arbuscular mycorrhizal fungi altered the hypericin, pseudohypericin, and hyperforin content in flowers of Hypericum perforatum grown under contrasting P availability in a highly organic substrate

St. John's Wort (Hypericum perforatum) is a perennial herb able to produce water-soluble active ingredients (a.i.), mostly in flowers, with a wide range of medicinal and biotechnological uses. However, information about the ability of arbuscular mycorrhizal fungi (AMF) to affect its biomass accumulation, flower production, and concentration of a.i. under contrasting nutrient availability is still scarce. In the present experiment, we evaluated the role of AMF on growth, flower production, and concentration of bioactive secondary metabolites (hypericin, pseudohypericin, and hyperforin) of H. perforatum under contrasting P availability. AMF stimulated the production of aboveground biomass under low P conditions and increased the production of root biomass. AMF almost halved the number of flowers per plant by means of a reduction of the number of flower-bearing stems per plant under high P availability and through a lower number of flowers per stem in the low-P treatment. Flower hyperforin concentration was 17.5% lower in mycorrhizal than in non-mycorrhizal plants. On the contrary, pseudohypericin and hypericin concentrations increased by 166.8 and 279.2%, respectively, with AMF under low P availability, whereas no effect of AMF was found under high P availability. These results have implications for modulating the secondary metabolite production of H. perforatum. However, further studies are needed to evaluate the competition for photosynthates between AMF and flowers at different nutrient availabilities for both plant and AM fungus.

Does the margin width influence recurrence rate in liver surgery for hepatocellular carcinoma smaller than 5 cm?

OBJECTIVE

Liver surgery is considered a curative treatment for hepatocellular carcinoma (HCC) but the importance of resection margin width remains controversial. The aim of this study is to clarify the role of 5-10 mm surgical margin width on post-operative recurrence and overall survival after resection.

PATIENTS AND METHODS

We analyzed recurrence rate and overall survival rate of 72 patients who underwent curative hepatic resection for HCC smaller than 5 cm with 5-10 mm surgical margin width between January 2005 and December 2014.

RESULTS

The mean follow-up period was 36 months. Among the seventy-two patients, thirty-one (31/72; 43%) developed recurrence but only eleven (11/31; 15.3%) along the resection margin. The disease-free survival was 77.2%, 50%, 41.4% at 1, 3 and 5 years respectively, and the overall survival was 89.9%, 78.8%, 60% at 1, 3 and 5 years respectively.

CONCLUSIONS

5-10 mm surgical resection margin for HCC smaller than 5 cm seems to be safe as a wider surgical margin because does not increase the risk of marginal recurrence and does not decrease overall survival rate. Further prospective and randomized studies are required to definitively clarify the importance of surgical margin width in hepatic resection for HCC.

The Aquamantys® system as alternative for parenchymal division and hemostasis in liver resection for hepatocellular carcinoma: a preliminary study

OBJECTIVE

To evaluate the clinical feasibility and safety of a new technique for liver resection using a new saline-coupled bipolar sealing device (Aquamantys®) that has shown high performance in the animal setting.

PATIENTS AND METHODS

Twelve Child-Pugh A cirrhotic patients with hepatocellular carcinoma underwent partial hepatectomies using Aquamantys®. Our primary end-point was to observe occurrence of early specific surgical complications as bleeding, biliary leakage and abscess development. Our secondary end-point was to evaluate local recurrence along resection margin after a minimum follow-up of 1 year.

RESULTS

One bisegmentectomy, five monosegmentectomies and six atypical resections were performed. Mean resection time was 45 minutes (range, 30-100 min). Mean blood loss was 20 mL (range 5-80 mL). Mean post-operative stay was 6 days (range 5-16 days). All specimens presented negative margins (R0) at pathological examination. No blood transfusion were required both intra-operatively and post-operatively. No mortality was observed within 30-days post-operatively. One fluid collection occurred after  6-7 bisegmentectomy and was successfully treated by ultrasound-guided percutaneous drainage. At 1 year follow-up two patients died: one because of new lesions into the liver and one because of distant metastases and multifocal new liver disease. Ten patient are alive disease free at 1 year follow-up.

CONCLUSIONS

Liver resection using Aquamantys® is feasible and safe and allows to achieve almost bloodless parenchymal division with minimal necrosis and negative margins even in atipycal resection. Comparative trials are needed to confirm our preliminary results.

[Radio-guided parathyroidectomy]

The Authors, after a careful review of literature about the instrumental diagnostic techniques (with particular attention to the nuclear-medical ones) and the surgical therapy of parathyroid diseases, report their experience on the use of the radio-guided mininvasive surgery with MIBI and gamma-probe for intraoperative localization of pathological glands. Once exposed their experience, the Authors conclude asserting that this technique is fast, slightly invasive and expensive, and certainly useful for the detection of pathological or ectopic glands. It can be widely employed because, in comparison to its numerous advantages, such as the reduction of the operating time and of the hospital-stay, the greater radicality and the possibility to use mininvasive techniques, it does not present significant technical limitations and/or radio-protectionistic problems.

Laparoscopic cholecystectomy in cirrhotic patients

BACKGROUND

This study aimed to evaluate the safety of laparoscopic cholecystectomy for patients with cirrhosis.

METHODS

The records of 22 laparoscopic cholecystectomies performed in patients with cirrhosis Child-Pugh A and B, from January 1995 to July 2001 were retrospectively reviewed.

RESULTS

No deaths occurred. Conversion to open cholecystectomy was necessary in two cases. The average operative time was 115 min, which was significantly shorter than that for patients undergoing open cholecystectomy. None of the patients required blood transfusion. Intraoperative problems occurred in two patients who experienced liver bed bleeding. Postoperative morbidity occurred in 36% of the patients and included hemorrhage, wound complications, intraabdominal collections, and cardiopulmonary complications, but all were controlled. The patients were dismissed after an average of 4 days.

CONCLUSION

The authors believe laparoscopic cholecystectomy can be performed safely in selected patients with cirrhosis Child-Pugh A and B who manifest indication for surgery. Laparoscopic cholecystectomy offers several advantages over open cholecystectomy: lower morbidity, shorter operative time, and reduced hospital stay.

[Intraperitoneal neoplastic dissemination of incidental gallbladder carcinoma after laparoscopic surgery]

BACKGROUND

Several laboratory and clinical studies have raised the concern that laparoscopic procedures might worsen the prognosis of patient with malignant disease due to premature intraperitoneal cancer cell dissemination. The aim of the study was to examine the risk of the dissemination in patients with unsuspected gallbladder cancer diagnosed after laparoscopic cholecystectomy (LC).

METHODS

A retrospective clinicopathologic study was performed on 5 patients with unsuspected gallbladder cancer without preoperatively diagnosis among 1280 patients that underwent LC in the period 1993-2002. The possible neoplastic dissemination was compared to that reported in 8 patients affected from unsuspected gallbladder cancer diagnosed after open cholecystectomy.

RESULTS

Two patients with unsuspected gallbladder cancer (T1a-T2) presented a port-site recurrence after respectively six and four months. There was not statistically significant difference between types of cholecystectomy (LC or OC). Survival rate did not change according to whether the operation was carried out using LC or OC.

CONCLUSION

After an accurate checking of the factors indicated to explain the early neoplastic dissemination frequently observed in the patients undergone LC and an analysis of their own experience the Authors conclude that LC does not worsen the prognosis of unsuspected gallbladder cancer.

[Subclavicular localization of Castleman's disease]

Castelman disease is a rare disease of lymph nodes. There are 2 pathological types: hyalo-vascular asymptomatic form and plasmacytic symptomatic form. Authors report a case of Castelman disease of a subclavicular lymph nodes that underwent surgical operation. Ethiopathogenesis and treatment of the disease are reported.

[Endoscopy in non-neoplastic cholestasis]

The role of endoscopic treatment of cholestasis is well codified as an alternative or adjuvant therapy to surgery, particularly in those cases where non malignant cause has been identified. Non-neoplastic cholestasis therefore benefits very substantially from endoscopic treatment in a context where the traditional surgical approach presents limitations in terms of morbidity and mortality. It should be borne in mind, however, that the two approaches are strictly complementary for the correct management of these patients.

[Aorto-esophageal fistula caused by foreign body]

Aortoesophageal fistula is a rare but fatal cause of upper gastrointestinal bleeding. AEF develop progressively from the esophageal perforation caused by foreign body. Clinically, there is a medial chest pain, followed by hematemesis and finally terminal exsanguination. Diagnosis must be achieved during the free intervals in this triad of often rapidly succeeding signs.

[The use of synthetic prosthesis in the treatment of hernia]

The authors report their experience on synthetic prosthesis used in 36 patients with abdominal hernias. Thirty six cases of incisional hernias have been analyzed by Institute of General Surgery of Messina University from 1992 to 1998. Among the 33 cases with median parietal defect, in 7 cases concerning great incisional hernias group a PTEF-e prosthesis, which was positioned in an intraperitoneal site, was employed. In 21 cases of medium size incisional hernias they used a polypropylene prosthesis, which was positioned in an intraparietal or preperitoneal site. In 5 cases of small size incisional hernias, polypropylene prosthesis was placed in a superfascial site. In the 3 cases of medium size lateral laparocele++, polypropylene prosthesis was positioned in a intraparietal site. There was no operative mortality. Among postoperative complications, 4 seromas, 1 parietal and 1 subcutaneous haematoma and 2 haematomas in retroperitoneal site appeared. Clinical-instrumental controls, which have continued until two or three years after the operation were performed which pointed out a recurrence in just one case where the prosthesis was positioned in a superfascial site. To conclude, we consider that nowadays the use of synthetic prosthesis lets us face and solve problems concerning surgical treatment of incisional hernias with confidence.

[Miles operation in rectal carcinoma: history and current status]

The Authors confirm how the advent of mechanical suture has directed the management of rectal carcinoma to an increasingly conservative attitude. In reporting their experience--which consists of about twenty years (222 patients) they specify how not only an increased incidence of recurrence has not appeared, but they have also observed a reduction of theirs (-5.2%). They then attempt to outline basic moments which have characterized the history of rectal carcinoma surgery and they state how today, 80 years since it was conceived, Miles' intervention maintains its validity, even if with more restrictive indications.

[Changes in serum levels of folic acid after total gastrectomy]

The Authors, in consideration that Folic Acid is assimilated in the upper alimentary tract, effected a comparative study between its seric levels in normal patients and in patients submitted to gastrectomy for gastric cancer, at different times from the operation. In the patients of the first group, Folic Acid levels were not correlated with sex, but to age, decreasing with the increasing of it. In gastrectomized patients, serum levels, also if acceptable, were always lower than in control cases, and gradually decreasing with the increasing of the age. The Authors conclude that, obviously, intestinal assimilation and endogenous reserves are able to counterbalance for enough long time the insufficient alimentary absorption.

[Surgical management of hereditary medullary carcinoma of the thyroid in patients with "RET" proto-oncogene mutation]

The authors report their results in 64 individuals belonging to 11 families with MEN 2 and familial medullary carcinoma of thyroid (CMT) syndromes. They show amplification and restriction techniques, type, site and incidence of genetic alteration in the observed cases; besides they illustrate the adopted surgical management related to the mutation. They stress the concept that genetic test allows to detect the population with altered gene before laboratory or clinical evidence, with the great advantage to indicate an early surgical approach. If it is shown a multi-organ disease, as in one patient with CMT associated with bilateral pheocromocytoma, the two diseases must be treated during the same operative time.

[Alpha-glucosidase and alanine-amino-peptidase in the early diagnosis of renal failure in obstructive jaundice]

Renal failure is a serious complication of obstructive jaundice. Early diagnosis and prevention of spontaneous evolution of the disease can improve prognosis, otherwise very poor in many cases. The Authors, on the basis of experimental researches from literature, expose their clinical experience about the validity of the determination of Alpha-Glucosidase and Alanine-Amino-Peptidase for early diagnosis and differentiation between organic or functional forms of renal failure. They conclude that determination of urinary levels of AGS and AAP is a valid aid for the evaluation of renal function in patients with obstructive jaundice.

[US or CT-guided percutaneous drainage of pancreatic pseudocyst]

Authors, after illustrating the pathogenesis of Pancreatic Pseudocysts (PPC) and classifying them into secondary to acute pancreatitis and arising in course of chronic pancreatitis, underline that the use of Ultrasound (US), CT-scan, Magnetic Resonance, Endoscopic Retrograde CholangioPancreatography and, above all, percutaneous drainage of the cysts has modified the therapeutic approach to this pathology. They describe indications and technique of US or CT-guided percutaneous drainage, and report their experience about 12 cases of PPC secondary to acute pancreatitis and 4 of PPC arising during chronic pancreatitis. They analyze the limits of this technique (risk of infections, recurrences, fistulas), and conclude that Percutaneous Drainage of Pancreatic Pseudocysts is a useful therapeutic approach in the treatment of PPC secondary to acute pancreatitis, while its use is complementary to surgery in the treatment of PPC due to chronic pancreatitis.

[Nuclear risk and thyroid neoplasms in infancy]

Thyroid carcinoma is a disease with low incidence in adult and rare in child. The authors give oncogenic risk factors of the disease and underline environment factors as iodine deficiency and radiation pollution that, as shown in certain world areas, has a strong effect in the epidemiology of this disease. Eventually radiation's are the most important oncogenic risk factors but and adequate iodine prophylactic program can be considered a valid shield to prevent this disease.

[Surgical problems in the aged patients]

Authors, considering the increasing of the middle duration of life and the increasing of geriatric population, examine various surgical problems in the elderly. They took in consideration not only the age, but all the other markers of surgical risk related to the surgical illness, to the associate illness and to the type of operation. After reporting their experience in the treatment of geriatric patients, they conclude that a scrupulous surgical preparation, a correct indication to the operation and an accurate overseeing after surgery are necessary to do that the elderly patient faces surgical intervention with the same capability of success of the young.

Pre and intra-operative methods of staging gastric cancer

The aim of this paper was to examine the indications and limits of pre- and intra-operative instrumental diagnosis of gastric cancer. In order to achieve this effectively, the authors emphasized the importance of proper staging methods and obtained a detailed description of tumor diffusion. The most important diagnostic instruments considered were magnetic resonance, endosonography, intra-operative echography, pre- and intra-operative immunoscintography and a cytological examination of peritoneal lavage fluid. The authors concluded that pre- and intra-operative staging of gastric cancer is important for two major reasons: it results in the most accurate definition possible of disease evolution, enabling a proper therapeutic program; and it involves a combination of three complementary metasurgical treatments.

[Primary adenocarcinoma of the duodenum]

Adenocarcinoma of the duodenum represents a rare neoplasia characterized by an indefinite symptomatology, at least early, and deceitful, that, therefore, arrives at surgeon, almost always, in advanced stage. The Authors, taking from a clinical case, recently observed, as a starting point, review the literature, referring the etiopathogenetic hypothesis that explain the relative rarity of this neoplasia. They therefore report the diagnostic and therapeutic procedure to carry out in these patients.

[Ambulatory treatment of inguinal hernia]

The Authors report their experience about the inguinal hernioplasty operation by implantation of prostheses in prolene following the Licthenstein technique. Prolene mesh strengthens the inguinal canal wall, with no suture tension point. The technique is performed under local anesthesia, in day-hospital system, consenting the patient a rapid reinstatement in the social-working ambit.

Cytodiagnosis in the management of extrahepatic biliary stricture

A total of 117 patients presenting with extrahepatic biliary strictures between 1981 and 1989 had 206 cytological examinations of the bile duct or bile (153 non-operative, 53 intraoperative) to establish the presence of malignancy. A final diagnosis of cholangiocarcinoma was made in 88 patients, with 29 patients having benign biliary strictures. The cytological techniques used were fine needle aspiration (n = 102) or brushing (n = 24) of the bile duct, or exfoliative cytology of bile (n = 80). Forty one patients with malignancy had two or more examinations with differing results between samples in 20 cases. The overall sensitivity was 72%. There was only one false positive result, giving a patient predictive value of positive cytology of 98%. Intraoperative cytology was more sensitive than non-operative examination (80% v 42%). Overall, the sensitivity of fine needle aspiration (67%) was greater than that of brush cytology (40%) or exfoliative cytology (30%). No complications were encountered. Cytodiagnosis of extrahepatic biliary strictures is a safe procedure which is not technically demanding, and as it has a high sensitivity and predictive value for positive cytology, cytological confirmation of malignancy should be sought in all clinically and radiologically suspicious cases.

[The usefulness of cytodiagnosis in nonpalpable breast lesions]

The paper underlines the importance of early diagnosis in the treatment of breast tumours and emphasises the value of cytodiagnosis as a very sensitive and specific predictive method for detecting impalpable lesions. In conclusion, the Authors affirm that cytodiagnosis, together with the introduction of new diagnostic instruments such as the TRC Mammotest, allows the diagnostic and therapeutical approach to impalpable breast tumours to be improved. It adds to the already high sensitivity of mammography and to the high predictive specificity of cytology, thus contributing to the reduction of the so-called "bioptic cost".

[Unilateral polycystic renal dysplasia]

The Authors report two cases of unilateral multicystic kidney dysplasia comparing the etiopathogenetic and clinical characteristics with those of polycystic kidney disease. They conclude with some considerations on the current therapeutic trend in these cases.

[Role of screening as an index of predictability in the early diagnosis of nonpalpable lesions of the breast]

The Authors, on the basis of their personal experience and supported by more significative data from the international literature, underline the validity of the screening in detecting non palpable lesions of the breast. They conclude by asserting that mortality for breast cancer may be further reduced if more and more women undergo screening programmes.

[Biliary peritonitis caused hy hydatid disease]

After specifying that rupture of a hydatid cyst in the peritoneal cavity is one of the most serious and rarest complications of hepatic hydatidosis, attention is paid to the peritoneal hydatid (o chole-hydatid). The aetiopathogenetic mechanisms and the anatomo-pathological features of this type of lesion are described in brief. Finally, the personally employed diagnostic protocol and therapeutic strategy in the face of this feared complication are reported.

[Malignant melanoma of the skin: current diagnostic and therapeutic approaches]

The Authors claim that the treatment of malignant melanosis of the skin is a problem of undiminished topical interest owing to its highly aggressive characteristics. Risk factors and pre-neoplastic lesions are reviewed, and the signs of malignant transformation are described along with the appropriate treatment. The Authors stress the importance, for therapeutic and prognostic purposes, of accurate clinical staging and macro- and microscopic study of the primary tumour. They also describe their own therapeutic approach, which involves the use of a CO2 laser for resecting the primary tumour. They present their patient population and conclude by observing that the progress achieved over the past decade is due both to earlier diagnosis and to improvements in the various therapeutic means available.

[Conservative surgical treatment of acute hemorrhagic necrotizing pancreatitis]

The Authors though in theirs' opinion medical treatment is the primary therapeutical approach to Acute Necrotizing Haemorrhagic Pancreatitis (A.N.H.P.), state that the surgical treatment is indicated as soon as the necrotizing haemorrhagic evolution of the disease is strongly suspected. It should be conservative in type acting on the evolution of the disease and saving the anatomic integrity of the pancreas. The surgical technique adopted is described which consists in removing cellular debris as well as highly toxic necrotic pancreatic apparatus and it is completed by the endo-retroperitoneal perfusion for a continuous washing of the peritoneal cavity. In conclusion, they report their personal experience with 16 patients affected with A.N.H.P.

[Sequential therapy with antiestrogens and progestational drugs in carcinoma of the breast in an advanced stage]

After discussing the mechanism of action of antioestrogens and medroxy-progesterone-acetate, the authors report on their experience with the sequential use of these two hormones in a group of patients with advanced cancer of the breast. After illustrating the results of their study, the authors conclude by stressing that the sequential use of these drugs appears to improve the quality of life of the patients with a significant increase in rates of complete or partial remission of the neoplastic disease.

[Use of tumor markers in monitoring thyroid carcinoma]

The authors report on their experience regarding the use of tumours markers for the pre-operative monitoring and subsequent follow-up of patients suffering from thyroid carcinoma. All patients were subjected to radio-immuno-assay for circulating thyroglobulin, a valuable indicator of residual and metastatic thyroid tissue. The patients suffering from medullary carcinoma of the thyroid and their immediate families were also monitored by periodic thyrocalcitonin assay. A further tumour marker assayed was CEA, levels of which are raised in the presence of thyroid neoplasms at an advanced or metastasizing stage. The authors conclude by presenting the results obtained and confirm the usefulness of these tumour markers in the study and follow-up of patients with thyroid carcinoma.

[Clinico-statistical features on the operative risk in old age]

The authors, after reporting the data concerning the increase of the average length of life and the increment of the population in geriatric age, studied the different aspects of the surgical risk. They consider the age, the existence or absence of associated diseases, the situation of the different organs or apparatuses, and the possibility to correct, in preoperative stage, the different functional unbalances remarked. At last, after confirming the conception whereby age for itself does not represent a specific factor of risk, they emphasize the importance of a multidisciplinary cooperation in the assistance to old patients, both during intervention and in the postoperative course.

[Principles of rehabilitation of colostomy patients]

The authors, after pointing out the number of enterostomized patients in the last years was more and more increasing, study all the repercussions of metabolic, functional and psychologic nature which are arising in the patients subjected to ultimate colostomy. Then, they describe the principles of a correct rehabilitative program for such patients, consisting in performing a correct colostimy and rigidly following hygienicodietetic rules. At last the authors, as a conclusion, affirm the rehabilitation, through the creation of proper centers with specialized staff, should also aim at the resolution of the remarkable psychologic problems affecting such patients, so as to have them reinserted in the social context they are coming from.

[Treatment of occlusions caused by carcinoma of the left colon in the aged]

The Authors, after pointing out that, in geriatric age, the incidence of left colon carcinoma has significantly increased, and this, in a high quantity of cases, goes unnoticed in precocious stage, but appears "d'emblée" pith an occlusive situation, state their experience concerning the surgical treatment of occlusions due to left colon carcinoma in patients aged over sixty. From the evaluation of the results they obtained, the Authors assert that, if the operation is performed after a correct appraisal of the patient's general conditions and after an adequate counterbalancing of the metabolic and functional alterations, often present in old people, the operative mortality, the postoperative complications and the indices of survival are not so significantly different from those remarked in the young subjects.

Human blood oscillating axially in a tube

Experiments were performed to study the rheological response of human blood at hematocrit ratios of 0 to 0.45 in axial oscillatory flow in a tube of uniform bore. Three principal regimes of flow were identified, depending on the amplitude of oscillation. At the highest amplitudes (and therefore the largest range of shear rates in the blood) there was turbulent motion and the friction coefficient increased in proportion to the square of the hematocrit. At small amplitudes the friction decreased with increase in amplitude, the rate of decrease increasing with hematocrit. At intermediate amplitudes the friction increased in proportion to the square of the hematocrit. Glutaraldehyde fixation of the red cells caused increase in the friction, and reduced the rate of decrease of friction with amplitude at small amplitudes. With a stenosis of very modest degree and span the friction in normal blood increased disproportionately, and a small blind hole in the lumen of the stenosis caused additional and disproportionate increase in friction.