Diabetes - kahi maʻi metabolic

ʻO ke kūlike ʻole a i ʻole ka hapa i ka insulin (ka nui o ka hewa o ka metabolic i ka maʻi diabetes) e alakaʻi i kahi hewa ʻole o nā ʻano metabolism, a ʻoi aku ka nui o nā mea āpau - mea kalea:

hoʻonui i ka gluconeogenesis ma muli o ka nalowale o ka hopena o ke keʻena o ka insulin i ka nui o nā enzyme gluconeogenesis,

hoʻonui i ka glycogenolysis ma lalo o ka mana o glucagon, hoʻonui ioneoneoneone a me glycogenolysis ka nui o ka glucose i loko o ke koko, a me

ka hoʻokaʻa ʻana ma o nā membranes i loko o nā ʻine pili i ka insulin e like me ka nele o ka insulin.

No laila, he mea kakaikahi he hanana nuii ka ʻike ʻana o ke kino i ka pōloli me ka nui o ka ikehu o ka ikehu o ka ikehu.

Hyperglycemia - ke kumu nui o ka maʻi maʻi - hoʻonui ʻōmole i ka plasmaa alakaʻi ihoʻoili pili. ^ E Ha yM. I ka hiki koke ʻana o ka paepae o nā renal no ka glucose (8-10 mmol / L), ua ʻike ʻia, i ka urine, e hoʻoiho anaglucosuriaapolyuria(nā hōʻailona o ka DM decompensation). Hoʻopili ʻia ka Polyuria me ka reabsorption impaired o ka wai a me ka electrolytes ma muli o ka osmolarity kiʻekiʻe o ka urine mua. ʻO Polyuria a me ka hyperosmia kumumakewaiapolydipsiaaoiaʻenocturia(nā hōʻailona o ka DM decompensation).

Hoʻokomo ʻia ka diuresis Osmotic i ka ʻeha huina pihaahuikihala. ^ E Ha yM. ʻO ka hopena o ka dehydrationhypovolemia, ka hoemi i ke koko, ke ʻano i ka piha ʻana o ka lolo, ʻōpū, ka hoʻohaʻahaʻa i nā koina filtration,oliguria(a hiki i ka hoʻomohala ʻana i ka maʻi renal paʻakikī). Eia kekahi, ma muli o ka maʻi wai, kūlohelohe o ke koko, wīwī, ulu nā ICE, a me nā ʻōnaehana microcirculation e alakaʻi i ka maʻihypoxiamau kiko.

Alakaʻi ʻo Hyperglycemia i ke hoʻoikaika manawa holo pololi(ma ka hana o ke aldoreductase). He mea hoʻonāukiuki iki o ka insulin me ka hoʻokumu ʻana o ka sorbitol a me ka fructose. Hoʻonohonoho kēia mau huahana i nā kūlohelohe pono ʻole o ka insulin (lens, nerve nerve, cell cells, red blood cells, vascular wall, basophilic insulocytes) a, me ka osmotic, ka huki wai ana, ka mea e hoʻopōʻino i kēia mau kiko.

Hyperglycemia ma o ka hōʻemi ʻana o sorbitol (a, no laila, e hōʻemi ana i nā mālama mālama NADPH2), a he hōʻemi hoʻi i ka hana o ka protein kinase C, alakaʻi i kahi hōʻemi i loko o ka hananitric oxide (ka hopena hoʻomaha hoʻomaha endothelial), ka mea e alakaʻi ai i ka vasoconstriction a me ka ischemia kiko,

Hiki pū ʻo Hyperglycemia i ʻōpūme ka hoʻomalolo ʻana o nā pā o ke koko (hyalinosis - ka hoʻokumu ʻana o glycoproteins, e hele ana ma lalo o ke kīpī palapa o nā capillaries, maʻalahi e hāʻule i waho a hānai ʻia).

Hoʻomoe ka Hyperglycemia i ke Kaʻina Hana glycosylation protein(glycosylation ka ʻano o ka pilina non-enzymatic o ka glucose me nā pūʻulu amino o nā protein). Ke hopena, ua hoʻokumu ʻia nā huahana glycosylation:

hemoglobin glycosylated. Ke loaʻa nei kahi pilina kiʻekiʻe no ka oxygen, ʻaʻole e hāʻawi iā ia i nā kiko, ulu ka hypoxia,

nā apoproteins glycosylated o LDL a me HDL, e alakaʻi ana i ka piʻi nui o ka pae o LDL / HDL.

glycosylation o ka protein o ka hoʻopihapiha a me nā ʻōnaehana anticoagulation, e alakaʻi ana i ka trombosis nui aʻe,

glycosylation o nā protein nui o ka membement basement a me collagen,

ka glycosylation o myelin, e alakaʻi i ka loli i loko o kāna ʻoihana o ka ʻāuna,

glycosylation o nā protein lens, ka mea e alakaʻi ai i ka cataracts,

glycosylation o nā protein transporter insulin, e alakaʻi ana i ka pale ʻana i ka insulin, etc.

Ua loli nā loli āpau o nā glycosylation āpau, ʻo ia ka mea e hiki ai iā lākou ke loaʻa nā waiwai antigenic, ma muli o ke ʻano o ka hoʻopale ʻana o ka autoimmune i nā kino kūpono a me nā ʻili.

ʻO ke kaila insulin ka mea i alakaʻi i ka hoʻolālā lactic acidosis. Nā mīkini:

ʻO ka hemahema o ka insulin e alakaʻi i ka pale ʻana o ka dehydrogenase pyruvate, ma muli o ke kumu ʻole o ka PVA e huli i AcCoA (e puhi i ka c. Krebs). I kēia kūlana, huli ka nui o PVC i lactate,

Hoʻonui ka insulin i ka protein catabolism, e alakaʻi ai i ka hoʻokumu ʻana o ka nui o nā substrates no ka hana o ka pyruvate a me ka lactate,

ʻO ka hypoxia kiko, a me ka nui o ka hana o nā hormone contrainsular (ʻoiaiʻo adrenaline a me STH) alakaʻi i ka hoʻōla o ka anaerobic glycolysis, ʻo ia ka hoʻonui i ka hoʻonuiʻana i ka lactate.

ʻO ka momona o ka momoname ka type 1 diabetes mellitus, pili lākou i ka nele ʻole o ka insulin a me ka hoʻonui ʻana i ka hana o nā hormones contrainsular. Ke alakaʻi nei kēia i ka emiʻana o ka hoʻohanaʻana i ka glucose e ka kiko adipose aʻo ka hoʻemi ʻana i ka lipogenesis a me ka hoʻomaikaʻi ʻana i ka lipolysis. (nā mea maʻi me ka maʻi diabetes type 1) he lahilahi.

I ke kumu, hua ketamine amino acid (leucine, isoleucine, valine) a me FFA i loko o ka ate, ma laila lākou i lilo ai i māka o ka synthesis nui o nā kino ketone (acetoacetic, b-hydroxybutyric, acetone). Ke ulu neihipehuinemia.

ʻO nā mea hoʻonaninani o nā kino ketone:

pale i ka synthesis o ka insulin a hana ole ia,

hoʻāʻo i ka membrane hoʻolaʻa manuahi, e hoʻomaikaʻi i ka ʻōpū o ka cell,

hoʻoweliweli i ka hana o nā kinemona he nui,

hoʻoweliweli i nā hana o ka ʻōnaehana o ka wahī,

kumu ka hoʻomohala ʻana o ka ketoacidosis,

kumu i ka hoʻolālā ʻana o ka hoʻihoʻi ʻana o ka ʻoihana,

hana i ka hemodynamics: ke kāohi i ka hoʻāla i myocardial a hōʻemi i ke koko koko ma muli o ka hoʻonui ʻia o nā moku peripheral.

ʻO ka huehue o ka protein proteinme ke maʻi me ka maʻi maʻamau i ka:

hoʻomaloʻa ʻia o ka protein synthesis (hana ʻia ka insulin i ka synthesis synthes) a

ka hoʻonui nui ʻana o kona uhai i ka ʻāʻī o ka naʻau (ke pale ʻana ka insulin i nā enzyme gluconeogenesis, me ka hapa ʻole o ka insulin, hele aku ʻo AK i ka hana o ka glucose),

Eia kekahi, hoʻomalu ʻo AK ma o nā membranes i hoʻopau ʻia.

Ke hopena, hoʻokumu ʻia ka hemahema o ka palaka i loko o ke kino, ka mea e alakaʻi ai i ka:

ka ulu ʻana o ka ulu ʻana o nā keiki

i ka nele i nā kaʻina hana,

hoʻōla hōʻeha

ho'ēmi i nā huahana Ati

ho'ēmi i ka pale i nā maʻi,

i ka manawa aʻe, ʻo ka hoʻololi i ka waiwai antigenic o nā protein kino e hiki ke hoʻoneʻe i nā kaʻina autoimmune.

ʻO nā hopena o ka Diabetesua māhele ʻia i loko o ke aʻa a me ka maʻi. ʻO nā hopena hoʻonā o ka maʻi maʻi - koma. ʻEha - nā angiopathies a me neuropathies.

Ua hoʻokaʻawale ʻia nā angiopathies Diabetic i nā micro- a me macroangiopathies.

Hoʻolālā Microangiopathies Diabetic - nā hoʻololi kulekele i nā moku o ka microvasculature.

ka hōʻiliʻili o nā sorbitol a me ka fructose i ka paia o ka moku,

nā huahana glycosylation o nā protein o ka membement basement,

hyalinosis o ka pā moku,

A ʻo kahi hopena, ua hoʻoneʻe ʻia ka hoʻolālā, metabolism a me nā hana o ka paia o ka moku, kū i ka ischemia kiko. ʻO nā ala nui o ka microangiopathies: retinopathy a me nephropathy.

Hoʻokomo ʻia i ka retinopathy Diabetic- microangiopathy o nā moku retinal, i ka papa hana i hiki ke hoʻopau i ka ʻike. ʻO nā Microaneurysms, maculopathy, hemorrous hemorrous. Nā hopena - detachment retinal, glaucoma kūloko.

Na ka papa ʻaina ʻOkopi- ka poino ʻole i ka microvasculature o nā moku o ka pūpū, i ukali ʻia e ka hoʻokumu o ka nodular a i ʻole e diffom glulerulosclerosis a me CRF i ka pūʻai hope.

Nā maʻi maʻi macroangiopathy- hōʻino i ka wahī o ke kīkala mololi.Nā mīkini:

glycosylation o ke kinapu o ka membrane protein,

ka hōʻiliʻili o nā sorbitol a me ka fructose i ka paia o ka moku,

Ke hoʻomaka nei kēia āpau i ka mānoanoa, hoʻemi i ka elasticity o ka paia o ka moku, hoʻonui nui hāmeʻa, nalowale o ka heparin receptors, hoʻonui i ke platelet adhesion, a me ka hoʻoulu ʻana i ka ea o ka cell cell proliferation, ʻo ia hoʻi i mua a hoʻonui ʻiahoʻomohalaatherosclerosis. ^ E Ha yM. ʻO nā ala nui i ka maʻi macroangiopathies maʻi:

no ka mea, ka pilikia o ka coronary, no laila, ka maʻi puʻuwai coronary a me ka hōʻeha o ka naʻau e like me ka hoʻopiʻi nui ʻana,

hana ino ʻia i nā moku cerebral i ke ʻano o nā hōʻeha, nā pilikia hōʻeha o ka sirkebral circulation a me dementia,

nā maʻi maʻamau o nā moku o nā haʻahaʻa haʻahaʻa ma ke ʻano o ka claudication intermittent, necrosis, gangrene.

ʻO ka neuropathy maʻi maʻi- hōʻino i ka hoʻonāukiuki i ka ʻōnaehana ma ka maʻi diabetes.

pelipal nerve protein glycosylation,

ka hoʻohālikelike ʻana o nā antibodies i nā protein i hoʻololi ʻia a me ka autoaggression e pili ana i nā antigens o ka io nūlū,

ka hōʻiliʻili ʻana o ka sorbitol a me ka fructose i loko o nā neurons a me nā ʻoihana ʻo Schwann,

hoʻemi i ka hoʻohuihui ʻole ʻana i ka pā o ka moku.

Ke hoʻomaka nei kēia āpau i ka haʻaleleʻole i ka hoʻokahe koko intraneural, kahi hoʻohaʻahaʻa i ka synthesis o myelin, a me kahi hoʻolohi i ka hana o nā neʻe a nerve. Nā ʻano o ka neuropathy diabetic:

Nā hana hōʻino a CNS (encephalopathy, myelopathy),

nā pōpilikia o nā nerve peripheral (polyneuropathy, mononeuropathy): nā helehelena a me nā pilikia sensory,

hana ʻino i ka nton autonomic (autonomic neuropathy): nā pilikia o ke hoʻoponopono ʻana o ka hana cardiac, leo vascular, ʻāpana ʻeha, gastrointestinal tract.

Hiki i nā Angiopathies a me nā neuropathies ke hopena i nā hoʻopiʻi maʻi e like me ka wāwae maʻi.

ʻO ka wāwae Diabetic- Ke ala o ke kuʻekuʻe o ka wāwae i ka maʻi maʻi maʻi, i hōʻailona ʻia e ka hōʻeha ʻana o ka ʻili a me nā palupalu palupalu, nā iwi a me nā ʻōpū a hōʻike ʻia i ke ʻano o nā ʻīlī trophic, hoʻololi i ka iwi a hui a me nā hana purulent-necrotic (a hiki i gangrene).

ʻO nā hopena hoʻonā o ka maʻi maʻi - koma.

I ka piko maʻi maʻi. ^ E Ha yM. ʻO ke kumu kumu o ka hoʻomohala ʻana i ka comic maʻi (DC) i ka maʻi diabetes, ʻaʻole ia ka maʻi diabetes me ia iho, no ka mea, ʻaʻole ia he ʻano paʻakikī i ka hoʻomohala ʻana i ka coma, akā,decomp dek.

Hoʻoulu i ka maʻi maʻi- kahi kūlana i ka hopena o ka metabola a me nā hana o ka maʻi i loaʻa i ka maʻi e hiki ke piʻi i kahi nui koʻikoʻi a hele pū ʻia me nā pilikia catastrophic o homeostasis: hyperosmolarity a me dehydration, dyselectrolythemia, ketoacidosis, lactic acidosis, hypoxia koʻikoʻi, a me kekahi mau mea o kēia mau hoʻololi i hiki ke mālama ʻiaʻohi ka naʻau, ka mea e alakaʻi ai i ka hoʻomohala koma.

Aia ma muli o ke ʻano o ka maʻi mellitus a me nā ʻano o ka mea hoʻonāukiuki, ʻoiai he ketoacidosis, a he hyperosmolarity, a i ʻole ka lactic acidosis e lanakila i ka maʻi maʻi. Ma kēiaʻike, aia nā koho 3 no DC:

keroʻiumoe pāpaʻaupō maʻamau

hipouium

Aia nā ʻano like ʻole o DC i nā pathogenesis like me ka decompensation o ka maʻi diabetes, akā naʻe me kahi nui o ka maʻi maʻamau i kēlā me kēia hihia.

ʻAno maʻi Kēkē 1 (IDDM)

ʻAʻole hana ke kino i ka insulin. Ke nānā nei kekahi poʻe i kēia ʻano he like me ka maʻi diabetes-dependant, diabetes ʻona a i ʻole ka hoʻomaka ʻana i ka maʻi diabetes. Hoʻopili pinepine ʻia nā pākaʻi type 1 ma mua o ka makahiki 40, ma ke ʻano ʻōpio mua a i ʻole nā ​​ʻōpio. ʻAʻole like ka maʻi maʻi type 1 e like me ke ʻano lua. Ma kahi o 10% o nā maʻi āpau o ka maʻi āpau he ʻano ʻokoʻa 1. ʻO nā mea maʻi me ka maʻi diabetes type 1 e hoʻoiho i ka insulin no ke koena o ko lākou ola. Pono lākou e mālama i nā pae kaila koko kūpono ma o ka hoʻokō ʻana i nā hoʻāʻo koko pinepine a me ka hahai ʻana i kahi meaʻai kūikawā. Eia nō naʻe, ke hoʻomau nei ka maʻi diabetes type 1, me ka ʻole o ka insulin i kēia maʻi, kahi ʻano ʻino nui koke o ke kīpē, a laila, he hopena hopena. ʻO nā hoʻopiʻi lōʻihi o ka maʻi maʻamau (ka hopena o ka angiopathy diabetes) hiki ke: makapō, hōʻeuʻeu ka naʻau, pilikia ʻole, hōʻeha ʻana o ka niho, dementia, ʻeha ʻeha trophic (a hiki i ka amputation o nā manamana).

ʻAno maʻi 2 (NIDDM)

ʻAʻole hana ke kino i ka nui o ka insulin no ka hana kūpono, ʻaʻole paha i pane mai nā pūna i ke kino me ka kū (insulin resisten). Ma kahi o 90% o nā maʻi maʻi maʻi āpau ma ka honua āpau ua loaʻa i ka maʻi diabetes type 2.

Hiki i kekahi poʻe ke mālama i kā lākou mau hōʻailona o ka maʻi diabetes type 2, nalo ke kaumaha, mālama i kaʻai olakino, hoʻomaʻamaʻa a mālama i ko lākou kaila o ka koko. Eia nō naʻe, he maʻamau ka ʻano o ka maʻi 2 - e loli nui ka ia - a pono e hoʻomanawanui ka mea maʻi i nā lāʻau e hoʻohiolo ana i ke kō, a i ʻole nā ​​mea inikini insulin.

ʻOi aku ka nui o ka poʻe kaumaha a me ka momona o ke kūkulu ʻana i ka ʻano 2 like me nā poʻe me ke kaumaha o ke kino. Loaʻa i ka poʻe me ka momona o loko, ʻike pū ʻia i ka waena o ke kikowaena, ka ʻōpū o ka ʻōpū, a me ka ʻōpū o ka ʻōpū, a ʻo ia nō ka hopena o ka hopena.

ʻOi aku ka nui o ka pilikia o ka hoʻomohala ʻana i ke ʻano type diabetes 2 a ʻo ko mākou ʻōpio. ʻAʻole maopopo i nā loea nā kumu, akā, ʻōlelo lākou, i ko mākou wā he nui, ʻike mākou i ka kaupaona ʻana a lilo i mea hoʻoikaika kino. ʻO ka poʻe he mau ʻohana pili ʻole he maʻi a loaʻa paha i ke ʻano 2 ke kūlana kiʻekiʻe loa no ka pale ʻana i ka maʻi.

Diabetes i ka wā hapai (gestational diabetes)

Hoʻopilikia kēia ʻano i ka wahine i ka wā hāpai. ʻO kekahi mau wahine ke kiʻekiʻe o ke koko koko nui, ʻaʻole hiki i ko lākou mau kino ke hana i ka nui o ka insulin e halihali i nā glucose āpau i nā sela, no ka holomua o ka pae o ka glucose. Hōʻike ʻia ka maʻi diabetes gestational i ka wā hāpai.

ʻO ka hapa nui o nā poʻe maʻi me ka maʻi maʻi i ka wā hāpai e hiki ke mālama i ko lākou maʻi ma o ka hoʻomaʻamaʻa a me kaʻai. Akā mau loa 10% -20% o lākou e pono e inu i nā lāʻau lapaʻau e mālama ai i ka glucose koko. ʻO ka maʻi hoʻohiehie a ʻole i hoʻopaʻa ʻia i ka wā hāpai a hiki ke hoʻonui i ka loaʻa o ka hōʻeha i ka wā hānau. Hānau nui ʻia kahi pēpē.

Ma kahi maʻi maʻi mua

Pono e hoʻolilo i ka nalo o ke kaumaha (ma ka liʻiliʻi o 5 a 10 hapa pakeneka o kou kaumaha hoʻomaka) hiki ke pale a hoʻohemo paha i ka maʻi diabetes a hoʻomaʻemaʻe paha i ka mua o ka maʻi diabetes. E ʻike: nā Probiotics e kū'ē i ka Obesity

ʻO ka hapa nui o nā mea maʻi me ka type 2 mua i loaʻa i kahi maʻi maʻi mua. ʻO ka hapa nui o nā maʻi maʻi maʻi ʻaʻohe ʻano hōʻailona. Hiki i kāu kauka ke nānā i kou koko e ʻike inā ʻoi aku ka kiʻekiʻe o ke koena o ke koko ma mua o ka maʻamau. Ma mua o ka maʻi diabetes, ʻoi aku ka nui o ka piʻi ʻana o ke koko ma mua o ka maʻamau, akā, ʻaʻole nui no ka maʻi ka maʻi maʻi. Hoʻopau ke kāpena i loko o ke kino i ka insulin. Ua hōʻike ʻia nā haʻawina ʻoiai ma ke kahua mua o ka maʻi diabetes, ua hala ʻia kekahi hewa i ka ʻōnaehana cardiovascular a me ka puʻuwai.

* No ka hana pono o nā waiwai o nā microorganisms probiotic i ka hana ʻana i nā lāʻau lapaʻau hou no ka mālama ʻana a me ka pale ʻana o ka maʻi ʻohiʻipiʻi a me ka maʻi diabetes, ʻike i ka wehewehe ʻana no ka probiotic "Bifikardio":

KAHAKAU ANA, INIULU MAU KUPANUI

KO ʻ 12 12 KA HOA MA KA WAI I KE KAHI

Ma muli o ke kaupaona ʻana ʻo ia kekahi o nā mea e hoʻoholo ai i ka hoʻomohala ʻana i ka maʻi diabetes, he mea kūpono ia e hoʻomaopopo pehea e hele ai kēia kaʻina i ke kino a me ka mea e hoʻonāukiuki ai.

ʻO ke algorithm algorithm hiki ke hōʻike i kēia: 1. ke manaʻo nei ʻoe e pili ana i ka meaʻai, 2. hoʻomaka ʻoe e hoʻokuʻu i ka insulin, 3. hāʻawi ka insulin i ke kino i hōʻailona no ka mālama i nā momona momona a ʻaʻole puhi iā lākou, hoʻokuʻu i ka ikehu, 4. makemake ʻoe pōloli, 5. piʻi mai ke kō o ke koko. 6. nā paʻamaka maʻalahi i loko o kou koko i ke ʻano o ka glucose; 7. hoʻomaka ʻoe e huna i ka insulin hou aʻe; ʻoi loa ka momona 12. loaʻa iā ʻoe ka momona

ʻO nā ʻōpala e hele mau ana mai nā loko o ke kino. A ke hoʻokuʻu nei mākou i kēlā mau moʻo i koe i loko o ke kino. Mālama ka momona i loko o ka pūna momona i loko o ke ʻano o ka triglycerides. Hoʻokumu ʻia nā triglycerides mai ʻekolu momona momona e hoʻopili ʻia e kahi molekoleka glycerol i loko o kahi puʻupuʻu momona. He nui loa lākou a puka i waho o nā membrane o nā mea momona, ʻaʻole like me nā moena momona, kahi e puka maʻalahi ai. I.e. ka ulu ʻana o ka triglycerides, ʻoi aku ka nui o nā ʻāpana, ʻoi aku ka nui o kākou.

Pūleapohola a (maʻalahi) a me ka paʻakikī. ʻO nā koina wikiwiki a māmā paha he mau pūhui e lilo ai i hoʻokahi a ʻelua mau molekule monosaccharide, a ʻo lākou ka maikaʻi loa i ka hopena o ka hoʻoulu.

Ua hoʻokaʻawale ʻia nā mau kālaiʻu maʻalahi i ʻelua mau pūʻulu:

  • ʻO Monosaccharides (glucose, fructose, galactose),
  • Disaccharides (sucrose, lactose, maltose)

Pāleʻaleʻa maʻalahi lawe koke ʻia e ka wailua i ka glucose i ke koko. Ma kēia e hāpai i ka hana o ka insulin.

Insulin - ʻO ia ka luna hoʻoponopono nui o ka hana ʻaʻama. Aia ia i kona pae inā e hoʻokaʻawale a hoʻokaʻawale paha nā pūpū i nā momona. Ke hoʻonui ka nui o ka insulin, hoʻāla ʻia ka lipoprotein lipase - (LPL), nona ke kaʻa o ka momona i loko o ka pū. I.e. ka nui o ka insulin e hua ana iā mākou, ʻo ka LPL ka mea ikaika i kā lākou ʻawaʻawa i nā ʻōpū me nā momona.

No laila, ʻo ka hana ʻana o ka isulin ma muli o nā hāmeʻa. ʻO ka nui a me nā momona o nā kalapona e hoʻopau i ka nui o ka momona e waiho ʻia.

A ʻo ia ka mea

hoʻonui ka kaloli i ka insulin -

- Ke hāpai nei ka insulin i ka hoʻohemo ʻana i ka momona

Ma ke kumuhana, e ʻike pū i:

E ola kino!

KOMIKALOKA MANA O PROBIOTIC DRUGS

Waiho I Kou ManaʻO HoʻOpuka